* [PATCH] pstore: Set tfm to NULL on free_buf_for_compression.
@ 2019-05-20 6:51 Pi-Hsun Shih
2019-05-20 16:30 ` Kees Cook
0 siblings, 1 reply; 2+ messages in thread
From: Pi-Hsun Shih @ 2019-05-20 6:51 UTC (permalink / raw)
Cc: Pi-Hsun Shih, Kees Cook, Anton Vorontsov, Colin Cross, Tony Luck,
open list
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>
---
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 75887a269b64..8355a46638d0 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;
--
2.21.0.1020.gf2820cf01a-goog
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [PATCH] pstore: Set tfm to NULL on free_buf_for_compression.
2019-05-20 6:51 [PATCH] pstore: Set tfm to NULL on free_buf_for_compression Pi-Hsun Shih
@ 2019-05-20 16:30 ` Kees Cook
0 siblings, 0 replies; 2+ messages in thread
From: Kees Cook @ 2019-05-20 16:30 UTC (permalink / raw)
To: Pi-Hsun Shih; +Cc: Anton Vorontsov, Colin Cross, Tony Luck, open list
On Mon, May 20, 2019 at 02:51:19PM +0800, Pi-Hsun Shih wrote:
> 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>
Thank you! Yes, without this, reloading pstore backend modules would
cause bad behavior. :)
Applied; will send to Linus shortly.
-Kees
> ---
> 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 75887a269b64..8355a46638d0 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;
> --
> 2.21.0.1020.gf2820cf01a-goog
>
--
Kees Cook
^ permalink raw reply [flat|nested] 2+ messages in thread
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2019-05-20 16:30 ` Kees Cook
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