Judging by commit 8ecb790ea8c3 ("ext4: avoid potential buffer over-read in parse_apply_sb_mount_options()"), the contents of s_mount_opts should be treated as __nonstring, i.e. there might be no NUL-terminator in the provided buffer. Then the same holds for the corresponding mount_opts field of the struct ext4_tune_sb_params exchanged with userspace via a recently implemented superblock tuning ioctl. The problem is that strscpy_pad() can't work properly with non-NUL-term strings. String fortifying infrastructure would complain if that happens. Commit 0efc5990bca5 ("string.h: Introduce memtostr() and memtostr_pad()") gives additional information in that regard. Both buffers are just raw arrays of the similar fixed size, essentially they should represent the same contents. As they don't necessarily have NUL-terminators, in both directions use plain memcpy() to copy their contents. Found by Linux Verification Center (linuxtesting.org). Fixes: 04a91570ac67 ("ext4: implemet new ioctls to set and get superblock parameters") Signed-off-by: Fedor Pchelkin --- The 1/2 patch of the current series fixes an issue existing only in 6.18-rc while 2/2 fixes the commit which was in turn backported to stable kernels. That's the reasoning for separation. fs/ext4/ioctl.c | 4 ++-- include/uapi/linux/ext4.h | 2 +- 2 files changed, 3 insertions(+), 3 deletions(-) diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c index a93a7baae990..c39b87d52cb0 100644 --- a/fs/ext4/ioctl.c +++ b/fs/ext4/ioctl.c @@ -1292,7 +1292,7 @@ static int ext4_ioctl_get_tune_sb(struct ext4_sb_info *sbi, ret.raid_stripe_width = le32_to_cpu(es->s_raid_stripe_width); ret.encoding = le16_to_cpu(es->s_encoding); ret.encoding_flags = le16_to_cpu(es->s_encoding_flags); - strscpy_pad(ret.mount_opts, es->s_mount_opts); + memcpy(ret.mount_opts, es->s_mount_opts, sizeof(ret.mount_opts)); ret.feature_compat = le32_to_cpu(es->s_feature_compat); ret.feature_incompat = le32_to_cpu(es->s_feature_incompat); ret.feature_ro_compat = le32_to_cpu(es->s_feature_ro_compat); @@ -1353,7 +1353,7 @@ static void ext4_sb_setparams(struct ext4_sb_info *sbi, es->s_encoding = cpu_to_le16(params->encoding); if (params->set_flags & EXT4_TUNE_FL_ENCODING_FLAGS) es->s_encoding_flags = cpu_to_le16(params->encoding_flags); - strscpy_pad(es->s_mount_opts, params->mount_opts); + memcpy(es->s_mount_opts, params->mount_opts, sizeof(es->s_mount_opts)); if (params->set_flags & EXT4_TUNE_FL_EDIT_FEATURES) { es->s_feature_compat |= cpu_to_le32(params->set_feature_compat_mask); diff --git a/include/uapi/linux/ext4.h b/include/uapi/linux/ext4.h index 411dcc1e4a35..8ed9acbd0e03 100644 --- a/include/uapi/linux/ext4.h +++ b/include/uapi/linux/ext4.h @@ -138,7 +138,7 @@ struct ext4_tune_sb_params { __u32 clear_feature_compat_mask; __u32 clear_feature_incompat_mask; __u32 clear_feature_ro_compat_mask; - __u8 mount_opts[64]; + __u8 mount_opts[64] __nonstring; __u8 pad[64]; }; -- 2.51.0