From a326e471ad46fde2079e75245057e5402e58a13f Mon Sep 17 00:00:00 2001 From: Pi-Hsun Shih Date: Mon, 20 May 2019 14:51:19 +0800 Subject: [PATCH] pstore: Set tfm to NULL on free_buf_for_compression 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: adf50fcbf2a0 ("pstore: Refactor compression initialization") Signed-off-by: Pi-Hsun Shih Cc: stable@vger.kernel.org Signed-off-by: Kees Cook --- fs/pstore/platform.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c index 75887a269b642..8355a46638d02 100644 --- a/fs/pstore/platform.c +++ b/fs/pstore/platform.c @@ -347,8 +347,10 @@ static void allocate_buf_for_compression(void) 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; -- 2.39.5