From 31ca7e77fd7efc3f98582bf682fcaadc31a7d505 Mon Sep 17 00:00:00 2001 From: Justin Stitt Date: Thu, 28 Mar 2024 21:16:52 +0000 Subject: [PATCH] reiserfs: replace deprecated strncpy with scnprintf strncpy() is deprecated for use on NUL-terminated destination strings [1] and as such we should prefer more robust and less ambiguous string interfaces. Our goal here is to get @namebuf populated with @name's contents but surrounded with quotes. There is some careful handling done to ensure we properly truncate @name so that we have room for a literal quote as well as a NUL-term. All this careful handling can be done with scnprintf using the dynamic string width specifier %.*s which allows us to pass in the max size for a source string. Doing this, we can put literal quotes in our format specifier and ensure @name is truncated to fit inbetween these quotes (-3 is from 2 quotes + 1 NUL-byte). All in all, we get to remove a deprecated use of strncpy and clean up this code nicely! 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: Signed-off-by: Justin Stitt Reviewed-by: Kees Cook Link: https://lore.kernel.org/r/20240328-strncpy-fs-reiserfs-item_ops-c-v1-1-2dab6d22a996@google.com Signed-off-by: Kees Cook --- fs/reiserfs/item_ops.c | 13 +++---------- 1 file changed, 3 insertions(+), 10 deletions(-) diff --git a/fs/reiserfs/item_ops.c b/fs/reiserfs/item_ops.c index 3a5a752d96c7..5011c10287c6 100644 --- a/fs/reiserfs/item_ops.c +++ b/fs/reiserfs/item_ops.c @@ -389,16 +389,9 @@ static void direntry_print_item(struct item_head *ih, char *item) name = item + deh_location(deh); if (name[namelen - 1] == 0) namelen = strlen(name); - namebuf[0] = '"'; - if (namelen > sizeof(namebuf) - 3) { - strncpy(namebuf + 1, name, sizeof(namebuf) - 3); - namebuf[sizeof(namebuf) - 2] = '"'; - namebuf[sizeof(namebuf) - 1] = 0; - } else { - memcpy(namebuf + 1, name, namelen); - namebuf[namelen + 1] = '"'; - namebuf[namelen + 2] = 0; - } + + scnprintf(namebuf, sizeof(namebuf), "\"%.*s\"", + (int)sizeof(namebuf)-3, name); printk("%d: %-15s%-15d%-15d%-15lld%-15lld(%s)\n", i, namebuf,