[PATCH v2] crypto: af_alg - Fix incorrect boolean values in af_alg_ctx

[PATCH v2] crypto: af_alg - Fix incorrect boolean values in af_alg_ctx

[Eric Biggers]

Commit 1b34cbbf4f01 ("crypto: af_alg - Disallow concurrent writes in
af_alg_sendmsg") changed some fields from bool to 1-bit bitfields of
type u32.  However, some assignments to these fields, specifically
'more' and 'merge', assign values greater than 1.  These relied on C's
implicit conversion to bool, such that zero becomes false and nonzero
becomes true.  With a 1-bit bitfields of type u32 instead, mod 2 of the
value is taken instead, resulting in 0 being assigned in some cases when
1 was intended.  Fix this by restoring the bool type.

Fixes: 1b34cbbf4f01 ("crypto: af_alg - Disallow concurrent writes in af_alg_sendmsg")
Cc: stable@vger.kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
---

v2: keep the bitfields and just change the type, as suggested by Linus

 include/crypto/if_alg.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/crypto/if_alg.h b/include/crypto/if_alg.h
index 0c70f3a555750..107b797c33ecf 100644
--- a/include/crypto/if_alg.h
+++ b/include/crypto/if_alg.h
@@ -150,11 +150,11 @@ struct af_alg_ctx {
 	struct crypto_wait wait;
 
 	size_t used;
 	atomic_t rcvused;
 
-	u32		more:1,
+	bool		more:1,
 			merge:1,
 			enc:1,
 			write:1,
 			init:1;
 

base-commit: cec1e6e5d1ab33403b809f79cd20d6aff124ccfe
-- 
2.51.0

Re: [PATCH v2] crypto: af_alg - Fix incorrect boolean values in af_alg_ctx

[Linus Torvalds]

On Wed, 24 Sept 2025 at 13:19, Eric Biggers <ebiggers@kernel.org> wrote:
>
> Fix this by restoring the bool type.

Applied directly since the end is nigh.

          Linus

Re: [PATCH v2] crypto: af_alg - Fix incorrect boolean values in af_alg_ctx

[Herbert Xu]

On Wed, Sep 24, 2025 at 01:18:22PM -0700, Eric Biggers wrote:
> Commit 1b34cbbf4f01 ("crypto: af_alg - Disallow concurrent writes in
> af_alg_sendmsg") changed some fields from bool to 1-bit bitfields of
> type u32.  However, some assignments to these fields, specifically
> 'more' and 'merge', assign values greater than 1.  These relied on C's
> implicit conversion to bool, such that zero becomes false and nonzero
> becomes true.  With a 1-bit bitfields of type u32 instead, mod 2 of the
> value is taken instead, resulting in 0 being assigned in some cases when
> 1 was intended.  Fix this by restoring the bool type.
> 
> Fixes: 1b34cbbf4f01 ("crypto: af_alg - Disallow concurrent writes in af_alg_sendmsg")
> Cc: stable@vger.kernel.org
> Signed-off-by: Eric Biggers <ebiggers@kernel.org>
> ---
> 
> v2: keep the bitfields and just change the type, as suggested by Linus
> 
>  include/crypto/if_alg.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Thanks for catching this and fixing it.  I wish there was a warning
for this.  Gcc will warn if a constant like 2 is assigned to the
bitfield, but there are no warnings if you assign an int to it.

Cheers,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt