The `strncpy` function is deprecated for NUL-terminated strings as explained in the "strncpy() on NUL-terminated strings" section of Documentation/process/deprecated.rst. In `xrep_symlink_salvage_inline()`, the `target_buf` (which is `sc->buf`) is intended to hold a NUL-terminated symlink path. The original code used `strncpy(target_buf, ifp->if_data, nr)`, where `nr` is the maximum number of bytes to copy. This approach is problematic because `strncpy()` does not guarantee NUL-termination if the source string is truncated exactly at `nr` bytes, which can lead to out-of-bounds read issues if the buffer is later treated as a NUL-terminated string. Evidence from `fs/xfs/scrub/symlink.c` (e.g., `strnlen(sc->buf, XFS_SYMLINK_MAXLEN)`) confirms that `sc->buf` is indeed expected to be NUL-terminated. Furthermore, `sc->buf` is allocated with `kvzalloc(XFS_SYMLINK_MAXLEN + 1, ...)`, explicitly reserving space for the NUL terminator. `strscpy()` is the proper replacement because it guarantees NUL-termination of the destination buffer, correctly handles the copy limit, and aligns with current kernel string-copying best practices. Other recommended functions like `strscpy_pad()`, `memcpy()`, or `memcpy_and_pad()` were not used because: - `strscpy_pad()` would unnecessarily zero-pad the entire buffer beyond the NUL terminator, which is not required as the function returns `nr` bytes. - `memcpy()` and `memcpy_and_pad()` do not guarantee NUL-termination, which is critical given `target_buf` is used as a NUL-terminated string. This change improves code safety and clarity by using a safer function for string copying. Signed-off-by: Marcelo Moreira <marcelomoreira1905@xxxxxxxxx> --- fs/xfs/scrub/symlink_repair.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/xfs/scrub/symlink_repair.c b/fs/xfs/scrub/symlink_repair.c index 953ce7be78dc..ce21c7f0ef54 100644 --- a/fs/xfs/scrub/symlink_repair.c +++ b/fs/xfs/scrub/symlink_repair.c @@ -185,7 +185,7 @@ xrep_symlink_salvage_inline( return 0; nr = min(XFS_SYMLINK_MAXLEN, xfs_inode_data_fork_size(ip)); - strncpy(target_buf, ifp->if_data, nr); + strscpy(target_buf, ifp->if_data, XFS_SYMLINK_MAXLEN + 1); return nr; } -- 2.50.0
