[PATCH] public_key: Add a comment to public_key_signature struct definition

[Roberto Sassu]

From: Roberto Sassu <roberto.sassu@xxxxxxxxxx>

public_key_verify_signature() calls sg_set_buf() to set the signature and
digest for the signature verification.

As sg_set_buf() requires the buffer to be in physically contiguous memory,
see commit ac4e97abce9b8 ("scatterlist: sg_set_buf() argument must be in
linear mapping"), mention that in a comment for the signature and digest
fields of the public_key_signature structure.

Link: https://lore.kernel.org/linux-integrity/Y4pIpxbjBdajymBJ@sol.localdomain/
Suggested-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
---
 include/crypto/public_key.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/crypto/public_key.h b/include/crypto/public_key.h
index 68f7aa2a7e55..6d623e063034 100644
--- a/include/crypto/public_key.h
+++ b/include/crypto/public_key.h
@@ -37,8 +37,8 @@ extern void public_key_free(struct public_key *key);
  */
 struct public_key_signature {
 	struct asymmetric_key_id *auth_ids[3];
-	u8 *s;			/* Signature */
-	u8 *digest;
+	u8 *s;			/* Signature (in physically contiguous mem) */
+	u8 *digest;		/* Digest (in physically contiguous mem) */
 	u32 s_size;		/* Number of bytes in signature */
 	u32 digest_size;	/* Number of bytes in digest */
 	const char *pkey_algo;
-- 
2.25.1