Re: general protection fault in af_alg_free_areq_sgls

On Tue, Nov 28, 2017 at 01:02:52AM -0800, Eric Biggers wrote:

quoted

From 1a7a7f86f09c50652f1fff75b8d3a32712826b32 Mon Sep 17 00:00:00 2001

From: Eric Biggers <redacted>
Date: Tue, 28 Nov 2017 00:46:24 -0800
Subject: [PATCH] crypto: af_alg - fix NULL pointer dereference in
 af_alg_free_areq_sgls()

If allocating the ->tsgl member of 'struct af_alg_async_req' failed,
during cleanup we dereferenced the NULL ->tsgl pointer in
af_alg_free_areq_sgls(), because ->tsgl_entries was nonzero.

Fix it by only freeing the ->tsgl list if it is non-NULL.

This affected both algif_skcipher and algif_aead.

Fixes: e870456d8e7c ("crypto: algif_skcipher - overhaul memory management")
Fixes: d887c52d6ae4 ("crypto: algif_aead - overhaul memory management")
Reported-by: syzbot <redacted>
Cc: <redacted> # v4.14+
Signed-off-by: Eric Biggers <redacted>

Patch applied.  Thanks.
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