From: Rabin Vincent Date: Fri, 19 Dec 2014 12:36:08 +0000 (+0100) Subject: crypto: af_alg - fix backlog handling X-Git-Tag: v3.2.67~80 X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=commitdiff_plain;h=61e8801c5ec3aebfafa10ef89873a18cd8aa3420 crypto: af_alg - fix backlog handling commit 7e77bdebff5cb1e9876c561f69710b9ab8fa1f7e upstream. If a request is backlogged, it's complete() handler will get called twice: once with -EINPROGRESS, and once with the final error code. af_alg's complete handler, unlike other users, does not handle the -EINPROGRESS but instead always completes the completion that recvmsg() is waiting on. This can lead to a return to user space while the request is still pending in the driver. If userspace closes the sockets before the requests are handled by the driver, this will lead to use-after-frees (and potential crashes) in the kernel due to the tfm having been freed. The crashes can be easily reproduced (for example) by reducing the max queue length in cryptod.c and running the following (from http://www.chronox.de/libkcapi.html) on AES-NI capable hardware: $ while true; do kcapi -x 1 -e -c '__ecb-aes-aesni' \ -k 00000000000000000000000000000000 \ -p 00000000000000000000000000000000 >/dev/null & done Signed-off-by: Rabin Vincent Signed-off-by: Herbert Xu Signed-off-by: Ben Hutchings --- diff --git a/crypto/af_alg.c b/crypto/af_alg.c index bf948e134981..6ef6e2ad344e 100644 --- a/crypto/af_alg.c +++ b/crypto/af_alg.c @@ -449,6 +449,9 @@ void af_alg_complete(struct crypto_async_request *req, int err) { struct af_alg_completion *completion = req->data; + if (err == -EINPROGRESS) + return; + completion->err = err; complete(&completion->completion); }