From 3ab6569af58314342d8630502cd783b2d0135914 Mon Sep 17 00:00:00 2001 From: Jake Daryll Obina Date: Fri, 22 Sep 2017 00:00:14 +0800 Subject: [PATCH] jffs2: Fix use-after-free bug in jffs2_iget()'s error handling path commit 5bdd0c6f89fba430e18d636493398389dadc3b17 upstream. If jffs2_iget() fails for a newly-allocated inode, jffs2_do_clear_inode() can get called twice in the error handling path, the first call in jffs2_iget() itself and the second through iget_failed(). This can result to a use-after-free error in the second jffs2_do_clear_inode() call, such as shown by the oops below wherein the second jffs2_do_clear_inode() call was trying to free node fragments that were already freed in the first jffs2_do_clear_inode() call. [ 78.178860] jffs2: error: (1904) jffs2_do_read_inode_internal: CRC failed for read_inode of inode 24 at physical location 0x1fc00c [ 78.178914] Unable to handle kernel paging request at virtual address 6b6b6b6b6b6b6b7b [ 78.185871] pgd = ffffffc03a567000 [ 78.188794] [6b6b6b6b6b6b6b7b] *pgd=0000000000000000, *pud=0000000000000000 [ 78.194968] Internal error: Oops: 96000004 [#1] PREEMPT SMP ... [ 78.513147] PC is at rb_first_postorder+0xc/0x28 [ 78.516503] LR is at jffs2_kill_fragtree+0x28/0x90 [jffs2] [ 78.520672] pc : [] lr : [] pstate: 60000105 [ 78.526757] sp : ffffff800cea38f0 [ 78.528753] x29: ffffff800cea38f0 x28: ffffffc01f3f8e80 [ 78.532754] x27: 0000000000000000 x26: ffffff800cea3c70 [ 78.536756] x25: 00000000dc67c8ae x24: ffffffc033d6945d [ 78.540759] x23: ffffffc036811740 x22: ffffff800891a5b8 [ 78.544760] x21: 0000000000000000 x20: 0000000000000000 [ 78.548762] x19: ffffffc037d48910 x18: ffffff800891a588 [ 78.552764] x17: 0000000000000800 x16: 0000000000000c00 [ 78.556766] x15: 0000000000000010 x14: 6f2065646f6e695f [ 78.560767] x13: 6461657220726f66 x12: 2064656c69616620 [ 78.564769] x11: 435243203a6c616e x10: 7265746e695f6564 [ 78.568771] x9 : 6f6e695f64616572 x8 : ffffffc037974038 [ 78.572774] x7 : bbbbbbbbbbbbbbbb x6 : 0000000000000008 [ 78.576775] x5 : 002f91d85bd44a2f x4 : 0000000000000000 [ 78.580777] x3 : 0000000000000000 x2 : 000000403755e000 [ 78.584779] x1 : 6b6b6b6b6b6b6b6b x0 : 6b6b6b6b6b6b6b6b ... [ 79.038551] [] rb_first_postorder+0xc/0x28 [ 79.042962] [] jffs2_do_clear_inode+0x88/0x100 [jffs2] [ 79.048395] [] jffs2_evict_inode+0x3c/0x48 [jffs2] [ 79.053443] [] evict+0xb0/0x168 [ 79.056835] [] iput+0x1c0/0x200 [ 79.060228] [] iget_failed+0x30/0x3c [ 79.064097] [] jffs2_iget+0x2d8/0x360 [jffs2] [ 79.068740] [] jffs2_lookup+0xe8/0x130 [jffs2] [ 79.073434] [] lookup_slow+0x118/0x190 [ 79.077435] [] walk_component+0xfc/0x28c [ 79.081610] [] path_lookupat+0x84/0x108 [ 79.085699] [] filename_lookup+0x88/0x100 [ 79.089960] [] user_path_at_empty+0x58/0x6c [ 79.094396] [] vfs_statx+0xa4/0x114 [ 79.098138] [] SyS_newfstatat+0x58/0x98 [ 79.102227] [] __sys_trace_return+0x0/0x4 [ 79.106489] Code: d65f03c0 f9400001 b40000e1 aa0103e0 (f9400821) The jffs2_do_clear_inode() call in jffs2_iget() is unnecessary since iget_failed() will eventually call jffs2_do_clear_inode() if needed, so just remove it. Fixes: 5451f79f5f81 ("iget: stop JFFS2 from using iget() and read_inode()") Reviewed-by: Richard Weinberger Signed-off-by: Jake Daryll Obina Signed-off-by: Al Viro Signed-off-by: Ben Hutchings --- fs/jffs2/fs.c | 1 - 1 file changed, 1 deletion(-) diff --git a/fs/jffs2/fs.c b/fs/jffs2/fs.c index 73652b2093b4..05f4ae6d4f03 100644 --- a/fs/jffs2/fs.c +++ b/fs/jffs2/fs.c @@ -352,7 +352,6 @@ error_io: ret = -EIO; error: mutex_unlock(&f->sem); - jffs2_do_clear_inode(c, f); iget_failed(inode); return ERR_PTR(ret); } -- 2.39.2