tcp: add tcp_min_snd_mss sysctl commit 5f3e2bf008c2221478101ee72f5cb4654b9fc363 upstream. Some TCP peers announce a very small MSS option in their SYN and/or SYN/ACK messages. This forces the stack to send packets with a very high network/cpu overhead. Linux has enforced a minimal value of 48. Since this value includes the size of TCP options, and that the options can consume up to 40 bytes, this means that each segment can include only 8 bytes of payload. In some cases, it can be useful to increase the minimal value to a saner value. We still let the default to 48 (TCP_MIN_SND_MSS), for compatibility reasons. Note that TCP_MAXSEG socket option enforces a minimal value of (TCP_MIN_MSS). David Miller increased this minimal value in commit c39508d6f118 ("tcp: Make TCP_MAXSEG minimum more correct.") from 64 to 88. We might in the future merge TCP_MIN_SND_MSS and TCP_MIN_MSS. CVE-2019-11479 -- tcp mss hardcoded to 48 Signed-off-by: Eric Dumazet <edumazet@google.com> Suggested-by: Jonathan Looney <jtl@netflix.com> Acked-by: Neal Cardwell <ncardwell@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Tyler Hicks <tyhicks@canonical.com> Cc: Bruce Curtis <brucec@netflix.com> Cc: Jonathan Lemon <jonathan.lemon@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net> [Salvatore Bonaccorso: Backport for context changes in 4.9.168] [bwh: Backported to 3.16: Make the sysctl global, consistent with net.ipv4.tcp_base_mss] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
tcp: limit payload size of sacked skbs commit 3b4929f65b0d8249f19a50245cd88ed1a2f78cff upstream. Jonathan Looney reported that TCP can trigger the following crash in tcp_shifted_skb() : BUG_ON(tcp_skb_pcount(skb) < pcount); This can happen if the remote peer has advertized the smallest MSS that linux TCP accepts : 48 An skb can hold 17 fragments, and each fragment can hold 32KB on x86, or 64KB on PowerPC. This means that the 16bit witdh of TCP_SKB_CB(skb)->tcp_gso_segs can overflow. Note that tcp_sendmsg() builds skbs with less than 64KB of payload, so this problem needs SACK to be enabled. SACK blocks allow TCP to coalesce multiple skbs in the retransmit queue, thus filling the 17 fragments to maximal capacity. CVE-2019-11477 -- u16 overflow of TCP_SKB_CB(skb)->tcp_gso_segs Backport notes, provided by Joao Martins <joao.m.martins@oracle.com> v4.15 or since commit 737ff314563 ("tcp: use sequence distance to detect reordering") had switched from the packet-based FACK tracking and switched to sequence-based. v4.14 and older still have the old logic and hence on tcp_skb_shift_data() needs to retain its original logic and have @fack_count in sync. In other words, we keep the increment of pcount with tcp_skb_pcount(skb) to later used that to update fack_count. To make it more explicit we track the new skb that gets incremented to pcount in @next_pcount, and we get to avoid the constant invocation of tcp_skb_pcount(skb) all together. Fixes: 832d11c5cd07 ("tcp: Try to restore large SKBs while SACK processing") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Jonathan Looney <jtl@netflix.com> Acked-by: Neal Cardwell <ncardwell@google.com> Reviewed-by: Tyler Hicks <tyhicks@canonical.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Bruce Curtis <brucec@netflix.com> Cc: Jonathan Lemon <jonathan.lemon@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net> [Salvatore Bonaccorso: Adjust for context changes to backport to 4.9.168] [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Merge branch 'stable-3.2' into pandora-3.2
ALSA: usb-audio: Fix parsing descriptor of UAC2 processing unit commit a6618f4aedb2b60932d766bd82ae7ce866e842aa upstream. Currently, the offsets in the UAC2 processing unit descriptor are calculated incorrectly. It causes an issue when connecting the device which provides such a feature: ~~~~ [84126.724420] usb 1-1.3.1: invalid Processing Unit descriptor (id 18) ~~~~ After this patch is applied, the UAC2 processing unit inits w/o this error. Fixes: 23caaf19b11e ("ALSA: usb-mixer: Add support for Audio Class v2.0") Signed-off-by: Kirill Marinushkin <k.marinushkin@gmail.com> Signed-off-by: Takashi Iwai <tiwai@suse.de> [bwh: Backported to 3.2: adjust filename] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
fs: Teach path_connected to handle nfs filesystems with multiple roots. commit 95dd77580ccd66a0da96e6d4696945b8cea39431 upstream. On nfsv2 and nfsv3 the nfs server can export subsets of the same filesystem and report the same filesystem identifier, so that the nfs client can know they are the same filesystem. The subsets can be from disjoint directory trees. The nfsv2 and nfsv3 filesystems provides no way to find the common root of all directory trees exported form the server with the same filesystem identifier. The practical result is that in struct super s_root for nfs s_root is not necessarily the root of the filesystem. The nfs mount code sets s_root to the root of the first subset of the nfs filesystem that the kernel mounts. This effects the dcache invalidation code in generic_shutdown_super currently called shrunk_dcache_for_umount and that code for years has gone through an additional list of dentries that might be dentry trees that need to be freed to accomodate nfs. When I wrote path_connected I did not realize nfs was so special, and it's hueristic for avoiding calling is_subdir can fail. The practical case where this fails is when there is a move of a directory from the subtree exposed by one nfs mount to the subtree exposed by another nfs mount. This move can happen either locally or remotely. With the remote case requiring that the move directory be cached before the move and that after the move someone walks the path to where the move directory now exists and in so doing causes the already cached directory to be moved in the dcache through the magic of d_splice_alias. If someone whose working directory is in the move directory or a subdirectory and now starts calling .. from the initial mount of nfs (where s_root == mnt_root), then path_connected as a heuristic will not bother with the is_subdir check. As s_root really is not the root of the nfs filesystem this heuristic is wrong, and the path may actually not be connected and path_connected can fail. The is_subdir function might be cheap enough that we can call it unconditionally. Verifying that will take some benchmarking and the result may not be the same on all kernels this fix needs to be backported to. So I am avoiding that for now. Filesystems with snapshots such as nilfs and btrfs do something similar. But as the directory tree of the snapshots are disjoint from one another and from the main directory tree rename won't move things between them and this problem will not occur. Reported-by: Al Viro <viro@ZenIV.linux.org.uk> Fixes: 397d425dc26d ("vfs: Test for and handle paths that are unreachable from their mnt_root") Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> [bwh: Backported to 3.2: - Add the super_block::s_iflags field - Adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
usb: quirks: add control message delay for 1b1c:1b20 commit cb88a0588717ba6c756cb5972d75766b273a6817 upstream. Corsair Strafe RGB keyboard does not respond to usb control messages sometimes and hence generates timeouts. Commit de3af5bf259d ("usb: quirks: add delay init quirk for Corsair Strafe RGB keyboard") tried to fix those timeouts by adding USB_QUIRK_DELAY_INIT. Unfortunately, even with this quirk timeouts of usb_control_msg() can still be seen, but with a lower frequency (approx. 1 out of 15): [ 29.103520] usb 1-8: string descriptor 0 read error: -110 [ 34.363097] usb 1-8: can't set config #1, error -110 Adding further delays to different locations where usb control messages are issued just moves the timeouts to other locations, e.g.: [ 35.400533] usbhid 1-8:1.0: can't add hid device: -110 [ 35.401014] usbhid: probe of 1-8:1.0 failed with error -110 The only way to reliably avoid those issues is having a pause after each usb control message. In approx. 200 boot cycles no more timeouts were seen. Addionaly, keep USB_QUIRK_DELAY_INIT as it turned out to be necessary to have the delay in hub_port_connect() after hub_port_init(). The overall boot time seems not to be influenced by these additional delays, even on fast machines and lightweight distributions. Fixes: de3af5bf259d ("usb: quirks: add delay init quirk for Corsair Strafe RGB keyboard") Signed-off-by: Danilo Krummrich <danilokrummrich@dk-develop.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
regulatory: add NUL to request alpha2 commit 657308f73e674e86b60509a430a46e569bf02846 upstream. Similar to the ancient commit a5fe8e7695dc ("regulatory: add NUL to alpha2"), add another byte to alpha2 in the request struct so that when we use nla_put_string(), we don't overrun anything. Fixes: 73d54c9e74c4 ("cfg80211: add regulatory netlink multicast group") Reported-by: Kees Cook <keescook@google.com> Signed-off-by: Johannes Berg <johannes.berg@intel.com> [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
nospec: Allow index argument to have const-qualified type commit b98c6a160a057d5686a8c54c79cc6c8c94a7d0c8 upstream. The last expression in a statement expression need not be a bare variable, quoting gcc docs The last thing in the compound statement should be an expression followed by a semicolon; the value of this subexpression serves as the value of the entire construct. and we already use that in e.g. the min/max macros which end with a ternary expression. This way, we can allow index to have const-qualified type, which will in some cases avoid the need for introducing a local copy of index of non-const qualified type. That, in turn, can prevent readers not familiar with the internals of array_index_nospec from wondering about the seemingly redundant extra variable, and I think that's worthwhile considering how confusing the whole _nospec business is. The expression _i&_mask has type unsigned long (since that is the type of _mask, and the BUILD_BUG_ONs guarantee that _i will get promoted to that), so in order not to change the type of the whole expression, add a cast back to typeof(_i). Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will.deacon@arm.com> Cc: linux-arch@vger.kernel.org Link: http://lkml.kernel.org/r/151881604837.17395.10812767547837568328.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
crypto: hash - prevent using keyed hashes without setting key commit 9fa68f620041be04720d0cbfb1bd3ddfc6310b24 upstream. Currently, almost none of the keyed hash algorithms check whether a key has been set before proceeding. Some algorithms are okay with this and will effectively just use a key of all 0's or some other bogus default. However, others will severely break, as demonstrated using "hmac(sha3-512-generic)", the unkeyed use of which causes a kernel crash via a (potentially exploitable) stack buffer overflow. A while ago, this problem was solved for AF_ALG by pairing each hash transform with a 'has_key' bool. However, there are still other places in the kernel where userspace can specify an arbitrary hash algorithm by name, and the kernel uses it as unkeyed hash without checking whether it is really unkeyed. Examples of this include: - KEYCTL_DH_COMPUTE, via the KDF extension - dm-verity - dm-crypt, via the ESSIV support - dm-integrity, via the "internal hash" mode with no key given - drbd (Distributed Replicated Block Device) This bug is especially bad for KEYCTL_DH_COMPUTE as that requires no privileges to call. Fix the bug for all users by adding a flag CRYPTO_TFM_NEED_KEY to the ->crt_flags of each hash transform that indicates whether the transform still needs to be keyed or not. Then, make the hash init, import, and digest functions return -ENOKEY if the key is still needed. The new flag also replaces the 'has_key' bool which algif_hash was previously using, thereby simplifying the algif_hash implementation. Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> [bwh: Backported to 3.2: - In hash_accept_parent_nokey(), update initialisation of ds to use tfm - Adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
crypto: hash - annotate algorithms taking optional key commit a208fa8f33031b9e0aba44c7d1b7e68eb0cbd29e upstream. We need to consistently enforce that keyed hashes cannot be used without setting the key. To do this we need a reliable way to determine whether a given hash algorithm is keyed or not. AF_ALG currently does this by checking for the presence of a ->setkey() method. However, this is actually slightly broken because the CRC-32 algorithms implement ->setkey() but can also be used without a key. (The CRC-32 "key" is not actually a cryptographic key but rather represents the initial state. If not overridden, then a default initial state is used.) Prepare to fix this by introducing a flag CRYPTO_ALG_OPTIONAL_KEY which indicates that the algorithm has a ->setkey() method, but it is not required to be called. Then set it on all the CRC-32 algorithms. The same also applies to the Adler-32 implementation in Lustre. Also, the cryptd and mcryptd templates have to pass through the flag from their underlying algorithm. Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> [bwh: Backported to 3.2: - Drop changes to nonexistent drivers - There's no CRYPTO_ALG_INTERNAL flag - Adjust filenames] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
crypto: hash - introduce crypto_hash_alg_has_setkey() commit cd6ed77ad5d223dc6299fb58f62e0f5267f7e2ba upstream. Templates that use an shash spawn can use crypto_shash_alg_has_setkey() to determine whether the underlying algorithm requires a key or not. But there was no corresponding function for ahash spawns. Add it. Note that the new function actually has to support both shash and ahash algorithms, since the ahash API can be used with either. Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
perf/hwpb: Invoke __perf_event_disable() if interrupts are already disabled commit 500ad2d8b01390c98bc6dce068bccfa9534b8212 upstream. While debugging a warning message on PowerPC while using hardware breakpoints, it was discovered that when perf_event_disable is invoked through hw_breakpoint_handler function with interrupts disabled, a subsequent IPI in the code path would trigger a WARN_ON_ONCE message in smp_call_function_single function. This patch calls __perf_event_disable() when interrupts are already disabled, instead of perf_event_disable(). Reported-by: Edjunior Barbosa Machado <emachado@linux.vnet.ibm.com> Signed-off-by: K.Prasad <Prasad.Krishnan@gmail.com> [naveen.n.rao@linux.vnet.ibm.com: v3: Check to make sure we target current task] Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Acked-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20120802081635.5811.17737.stgit@localhost.localdomain [ Fixed build error on MIPS. ] Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
sctp: Fix mangled IPv4 addresses on a IPv6 listening socket commit 9302d7bb0c5cd46be5706859301f18c137b2439f upstream. sctp_v4_map_v6 was subtly writing and reading from members of a union in a way the clobbered data it needed to read before it read it. Zeroing the v6 flowinfo overwrites the v4 sin_addr with 0, meaning that every place that calls sctp_v4_map_v6 gets ::ffff:0.0.0.0 as the result. Reorder things to guarantee correct behaviour no matter what the union layout is. This impacts user space clients that open an IPv6 SCTP socket and receive IPv4 connections. Prior to 299ee user space would see a sockaddr with AF_INET and a correct address, after 299ee the sockaddr is AF_INET6, but the address is wrong. Fixes: 299ee123e198 (sctp: Fixup v4mapped behaviour to comply with Sock API) Signed-off-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Neil Horman <nhorman@tuxdriver.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
x86: fix build warnign with 32-bit PAE I ran into a 4.9 build warning in randconfig testing, starting with the KAISER patches: arch/x86/kernel/ldt.c: In function 'alloc_ldt_struct': arch/x86/include/asm/pgtable_types.h:208:24: error: large integer implicitly truncated to unsigned type [-Werror=overflow] #define __PAGE_KERNEL (__PAGE_KERNEL_EXEC | _PAGE_NX) ^ arch/x86/kernel/ldt.c:81:6: note: in expansion of macro '__PAGE_KERNEL' __PAGE_KERNEL); ^~~~~~~~~~~~~ I originally ran into this last year when the patches were part of linux-next, and tried to work around it by using the proper 'pteval_t' types consistently, but that caused additional problems. This takes a much simpler approach, and makes the argument type of the dummy helper always 64-bit, which is wide enough for any page table layout and won't hurt since this call is just an empty stub anyway. Fixes: 8f0baadf2bea ("kaiser: merged update") Signed-off-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Kees Cook <keescook@chromium.org> Acked-by: Hugh Dickins <hughd@google.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
nospec: Include <asm/barrier.h> dependency commit eb6174f6d1be16b19cfa43dac296bfed003ce1a6 upstream. The nospec.h header expects the per-architecture header file <asm/barrier.h> to optionally define array_index_mask_nospec(). Include that dependency to prevent inadvertent fallback to the default array_index_mask_nospec() implementation. The default implementation may not provide a full mitigation on architectures that perform data value speculation. Reported-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will.deacon@arm.com> Cc: linux-arch@vger.kernel.org Link: http://lkml.kernel.org/r/151881605404.17395.1341935530792574707.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org> [bwh: Backported to 3.2: include <asm/system.h> instead] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
nospec: Kill array_index_nospec_mask_check() commit 1d91c1d2c80cb70e2e553845e278b87a960c04da upstream. There are multiple problems with the dynamic sanity checking in array_index_nospec_mask_check(): * It causes unnecessary overhead in the 32-bit case since integer sized @index values will no longer cause the check to be compiled away like in the 64-bit case. * In the 32-bit case it may trigger with user controllable input when the expectation is that should only trigger during development of new kernel enabling. * The macro reuses the input parameter in multiple locations which is broken if someone passes an expression like 'index++' to array_index_nospec(). Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will.deacon@arm.com> Cc: linux-arch@vger.kernel.org Link: http://lkml.kernel.org/r/151881604278.17395.6605847763178076520.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
nospec: Move array_index_nospec() parameter checking into separate macro commit 8fa80c503b484ddc1abbd10c7cb2ab81f3824a50 upstream. For architectures providing their own implementation of array_index_mask_nospec() in asm/barrier.h, attempting to use WARN_ONCE() to complain about out-of-range parameters using WARN_ON() results in a mess of mutually-dependent include files. Rather than unpick the dependencies, simply have the core code in nospec.h perform the checking for us. Signed-off-by: Will Deacon <will.deacon@arm.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1517840166-15399-1-git-send-email-will.deacon@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
x86/retpoline: Avoid retpolines for built-in __init functions commit 66f793099a636862a71c59d4a6ba91387b155e0c upstream. There's no point in building init code with retpolines, since it runs before any potentially hostile userspace does. And before the retpoline is actually ALTERNATIVEd into place, for much of it. Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: karahmed@amazon.de Cc: peterz@infradead.org Cc: bp@alien8.de Link: https://lkml.kernel.org/r/1517484441-1420-2-git-send-email-dwmw@amazon.co.uk [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
vfs, fdtable: Prevent bounds-check bypass via speculative execution commit 56c30ba7b348b90484969054d561f711ba196507 upstream. 'fd' is a user controlled value that is used as a data dependency to read from the 'fdt->fd' array. In order to avoid potential leaks of kernel memory values, block speculative execution of the instruction stream that could issue reads based on an invalid 'file *' returned from __fcheck_files. Co-developed-by: Elena Reshetova <elena.reshetova@intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: linux-arch@vger.kernel.org Cc: kernel-hardening@lists.openwall.com Cc: gregkh@linuxfoundation.org Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: torvalds@linux-foundation.org Cc: alan@linux.intel.com Link: https://lkml.kernel.org/r/151727418500.33451.17392199002892248656.stgit@dwillia2-desk3.amr.corp.intel.com [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
array_index_nospec: Sanitize speculative array de-references commit f3804203306e098dae9ca51540fcd5eb700d7f40 upstream. array_index_nospec() is proposed as a generic mechanism to mitigate against Spectre-variant-1 attacks, i.e. an attack that bypasses boundary checks via speculative execution. The array_index_nospec() implementation is expected to be safe for current generation CPUs across multiple architectures (ARM, x86). Based on an original implementation by Linus Torvalds, tweaked to remove speculative flows by Alexei Starovoitov, and tweaked again by Linus to introduce an x86 assembly implementation for the mask generation. Co-developed-by: Linus Torvalds <torvalds@linux-foundation.org> Co-developed-by: Alexei Starovoitov <ast@kernel.org> Suggested-by: Cyril Novikov <cnovikov@lynx.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: linux-arch@vger.kernel.org Cc: kernel-hardening@lists.openwall.com Cc: Peter Zijlstra <peterz@infradead.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Russell King <linux@armlinux.org.uk> Cc: gregkh@linuxfoundation.org Cc: torvalds@linux-foundation.org Cc: alan@linux.intel.com Link: https://lkml.kernel.org/r/151727414229.33451.18411580953862676575.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Ben Hutchings <ben@decadent.org.uk>