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ext4: Use memtostr_pad() for s_volume_name

PATCH Applied Kees Cook 2 participants 2 messages May 23, 2024 – Jul 11, 2024 ext4 file system

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Kees Cook

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PATCH 1/1 ext4: Use memtostr_pad() for s_volume_name

As with the other strings in struct ext4_super_block, s_volume_name is not NUL terminated. The other strings were marked in commit 072ebb3bffe6 ("ext4: add nonstring annotations to ext4.h"). Using strscpy() isn't the right replacement for strncpy(); it should use memtostr_pad() instead.

Reported-by [email protected]
Closes https://lore.kernel.org/all/[email protected]/ open here
Fixes 744a56389f73 ("ext4: replace deprecated strncpy with alternatives")
Signed-off-by Kees Cook <[email protected]>

---
Cc: "Theodore Ts'o" <[email protected]>
Cc: Justin Stitt <[email protected]>
Cc: Andreas Dilger <[email protected]>
Cc: [email protected]

---
 fs/ext4/ext4.h  | 2 +-
 fs/ext4/ioctl.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)
fs/ext4/ext4.h +1 -1
index 983dad8c07ec..efed7f09876d 100644
@@ -1347,7 +1347,7 @@ struct ext4_super_block {
 /*60*/	__le32	s_feature_incompat;	/* incompatible feature set */
 	__le32	s_feature_ro_compat;	/* readonly-compatible feature set */
 /*68*/	__u8	s_uuid[16];		/* 128-bit uuid for volume */
-/*78*/	char	s_volume_name[EXT4_LABEL_MAX];	/* volume name */
+/*78*/	char	s_volume_name[EXT4_LABEL_MAX] __nonstring; /* volume name */
 /*88*/	char	s_last_mounted[64] __nonstring;	/* directory where last mounted */
 /*C8*/	__le32	s_algorithm_usage_bitmap; /* For compression */
 	/*
fs/ext4/ioctl.c +1 -1
index dab7acd49709..e8bf5972dd47 100644
@@ -1151,7 +1151,7 @@ static int ext4_ioctl_getlabel(struct ext4_sb_info *sbi, char __user *user_label
 	BUILD_BUG_ON(EXT4_LABEL_MAX >= FSLABEL_MAX);
 
 	lock_buffer(sbi->s_sbh);
-	strscpy_pad(label, sbi->s_es->s_volume_name);
+	memtostr_pad(label, sbi->s_es->s_volume_name);
 	unlock_buffer(sbi->s_sbh);
 
 	if (copy_to_user(user_label, label, sizeof(label)))
Signature · 1 line
2.34.1
maintainer Applied
#1 lore raw
Quoted 8 lines · Kees Cook

As with the other strings in struct ext4_super_block, s_volume_name is not NUL terminated. The other strings were marked in commit 072ebb3bffe6 ("ext4: add nonstring annotations to ext4.h"). Using strscpy() isn't the right replacement for strncpy(); it should use memtostr_pad() instead.

[...]

Applied, thanks!

[1/1] ext4: Use memtostr_pad() for s_volume_name

      commit: be27cd64461c45a6088a91a04eba5cd44e1767ef

Best regards,

Signature · 1 line
Theodore Ts'o <[email protected]>