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| author | Justin Stitt <justinstitt@google.com> | 2024-03-21 02:03:10 +0100 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2024-05-03 05:55:10 +0200 |
| commit | 744a56389f7398f286231e062c2e63f0de01bcc6 (patch) | |
| tree | 845892d3d71e117f9b4161188ac04efa0798592e /fs/ext4/file.c | |
| parent | ext4: clean up s_mb_rb_lock to fix build warnings with C=1 (diff) | |
| download | linux-744a56389f7398f286231e062c2e63f0de01bcc6.tar.xz linux-744a56389f7398f286231e062c2e63f0de01bcc6.zip | |
ext4: replace deprecated strncpy with alternatives
strncpy() is deprecated for use on NUL-terminated destination strings
[1] and as such we should prefer more robust and less ambiguous string
interfaces.
in file.c:
s_last_mounted is marked as __nonstring meaning it does not need to be
NUL-terminated. Let's instead use strtomem_pad() to copy bytes from the
string source to the byte array destination -- while also ensuring to
pad with zeroes.
in ioctl.c:
We can drop the memset and size argument in favor of using the new
2-argument version of strscpy_pad() -- which was introduced with Commit
e6584c3964f2f ("string: Allow 2-argument strscpy()"). This guarantees
NUL-termination and NUL-padding on the destination buffer -- which seems
to be a requirement judging from this comment:
| static int ext4_ioctl_getlabel(struct ext4_sb_info *sbi, char __user *user_label)
| {
| char label[EXT4_LABEL_MAX + 1];
|
| /*
| * EXT4_LABEL_MAX must always be smaller than FSLABEL_MAX because
| * FSLABEL_MAX must include terminating null byte, while s_volume_name
| * does not have to.
| */
in super.c:
s_first_error_func is marked as __nonstring meaning we can take the same
approach as in file.c; just use strtomem_pad()
Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Justin Stitt <justinstitt@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20240321-strncpy-fs-ext4-file-c-v1-1-36a6a09fef0c@google.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'fs/ext4/file.c')
| -rw-r--r-- | fs/ext4/file.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/fs/ext4/file.c b/fs/ext4/file.c index 965febab1d04..77529c655f95 100644 --- a/fs/ext4/file.c +++ b/fs/ext4/file.c @@ -844,8 +844,7 @@ static int ext4_sample_last_mounted(struct super_block *sb, if (err) goto out_journal; lock_buffer(sbi->s_sbh); - strncpy(sbi->s_es->s_last_mounted, cp, - sizeof(sbi->s_es->s_last_mounted)); + strtomem_pad(sbi->s_es->s_last_mounted, cp, 0); ext4_superblock_csum_set(sb); unlock_buffer(sbi->s_sbh); ext4_handle_dirty_metadata(handle, NULL, sbi->s_sbh); |