crypto: lrw - don't access already-freed walk.iv

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If the user-provided IV needs to be aligned to the algorithm's
alignmask, then skcipher_walk_virt() copies the IV into a new aligned
buffer walk.iv.  But skcipher_walk_virt() can fail afterwards, and then
if the caller unconditionally accesses walk.iv, it's a use-after-free.

Fix this in the LRW template by checking the return value of
skcipher_walk_virt().

This bug was detected by my patches that improve testmgr to fuzz
algorithms against their generic implementation.  When the extra
self-tests were run on a KASAN-enabled kernel, a KASAN use-after-free
splat occured during lrw(aes) testing.

Fixes: c778f96bf3 ("crypto: lrw - Optimize tweak computation")
Cc: <stable@vger.kernel.org> # v4.20+
Cc: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

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Eric Biggers 2019-04-09 23:46:29 -07:00 • committed by Herbert Xu

parent 11fe71f146

commit aec286cd36

1 changed files with 3 additions and 1 deletions

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crypto/lrw.c

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