From: Fredric Cover Date: Mon, 30 Mar 2026 20:11:27 +0000 (-0700) Subject: fs/smb/client: fix out-of-bounds read in cifs_sanitize_prepath X-Git-Tag: v7.0-rc7~23^2 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=78ec5bf2f589ec7fd8f169394bfeca541b077317;p=thirdparty%2Flinux.git fs/smb/client: fix out-of-bounds read in cifs_sanitize_prepath When cifs_sanitize_prepath is called with an empty string or a string containing only delimiters (e.g., "/"), the current logic attempts to check *(cursor2 - 1) before cursor2 has advanced. This results in an out-of-bounds read. This patch adds an early exit check after stripping prepended delimiters. If no path content remains, the function returns NULL. The bug was identified via manual audit and verified using a standalone test case compiled with AddressSanitizer, which triggered a SEGV on affected inputs. Signed-off-by: Fredric Cover Reviewed-by: Henrique Carvalho <[2]henrique.carvalho@suse.com> Signed-off-by: Steve French --- diff --git a/fs/smb/client/fs_context.c b/fs/smb/client/fs_context.c index a4a7c7eee038..a46764c24710 100644 --- a/fs/smb/client/fs_context.c +++ b/fs/smb/client/fs_context.c @@ -588,6 +588,10 @@ char *cifs_sanitize_prepath(char *prepath, gfp_t gfp) while (IS_DELIM(*cursor1)) cursor1++; + /* exit in case of only delimiters */ + if (!*cursor1) + return NULL; + /* copy the first letter */ *cursor2 = *cursor1;