Messages in this thread Patch in this message | | | Date | Mon, 01 Apr 2024 20:01:51 +0000 | Subject | [PATCH] udf: replace deprecated strncpy/strcpy with strscpy | From | Justin Stitt <> |
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strncpy() is deprecated for use on NUL-terminated destination strings [1] and as such we should prefer more robust and less ambiguous string interfaces. Also replace an instance of strcpy() which is also deprecated.
s_volume_ident is a NUL-terminated string which is evident from its usage in udf_debug: | udf_debug("volIdent[] = '%s'\n", UDF_SB(sb)->s_volume_ident);
s_volume_ident should also be NUL-padded as it is copied out to userspace: | if (copy_to_user((char __user *)arg, | UDF_SB(inode->i_sb)->s_volume_ident, 32)) | return -EFAULT;
Considering the above, a suitable replacement is `strscpy_pad` [2] due to the fact that it guarantees both NUL-termination and NUL-padding on the destination buffer.
To simplify the code, let's use the new 2-argument version of strscpy_pad() introduced in Commit e6584c3964f2f ("string: Allow 2-argument strscpy()"). Also zero-allocate @outstr so we can safely use a non-@ret length argument. This is just in case udf_dstrCS0toChar() doesn't include the NUL-byte in its return length, we won't truncate @outstr or write garbage bytes either.
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> --- Note: build-tested only.
Found with: $ rg "strncpy\(" --- fs/udf/super.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/fs/udf/super.c b/fs/udf/super.c index 2217f7ed7a49..77d32fe14434 100644 --- a/fs/udf/super.c +++ b/fs/udf/super.c @@ -895,7 +895,7 @@ static int udf_load_pvoldesc(struct super_block *sb, sector_t block) int ret; struct timestamp *ts; - outstr = kmalloc(128, GFP_KERNEL); + outstr = kzalloc(128, GFP_KERNEL); if (!outstr) return -ENOMEM; @@ -921,11 +921,11 @@ static int udf_load_pvoldesc(struct super_block *sb, sector_t block) ret = udf_dstrCS0toChar(sb, outstr, 31, pvoldesc->volIdent, 32); if (ret < 0) { - strcpy(UDF_SB(sb)->s_volume_ident, "InvalidName"); + strscpy_pad(UDF_SB(sb)->s_volume_ident, "InvalidName"); pr_warn("incorrect volume identification, setting to " "'InvalidName'\n"); } else { - strncpy(UDF_SB(sb)->s_volume_ident, outstr, ret); + strscpy_pad(UDF_SB(sb)->s_volume_ident, outstr); } udf_debug("volIdent[] = '%s'\n", UDF_SB(sb)->s_volume_ident); --- base-commit: 928a87efa42302a23bb9554be081a28058495f22 change-id: 20240401-strncpy-fs-udf-super-c-983457eb4ac3 Best regards, -- Justin Stitt <justinstitt@google.com>
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