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Subject[PATCH 5.1 33/70] pstore: Set tfm to NULL on free_buf_for_compression
Date
From: Pi-Hsun Shih <pihsun@chromium.org>

commit a9fb94a99bb515d8720ba8440ce3aba84aec80f8 upstream.

Set tfm to NULL on free_buf_for_compression() after crypto_free_comp().

This avoid a use-after-free when allocate_buf_for_compression()
and free_buf_for_compression() are called twice. Although
free_buf_for_compression() freed the tfm, allocate_buf_for_compression()
won't reinitialize the tfm since the tfm pointer is not NULL.

Fixes: 95047b0519c1 ("pstore: Refactor compression initialization")
Signed-off-by: Pi-Hsun Shih <pihsun@chromium.org>
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/pstore/platform.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -347,8 +347,10 @@ static void allocate_buf_for_compression

static void free_buf_for_compression(void)
{
- if (IS_ENABLED(CONFIG_PSTORE_COMPRESS) && tfm)
+ if (IS_ENABLED(CONFIG_PSTORE_COMPRESS) && tfm) {
crypto_free_comp(tfm);
+ tfm = NULL;
+ }
kfree(big_oops_buf);
big_oops_buf = NULL;
big_oops_buf_sz = 0;

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