From 86aadcb0c68f4122793520bff07dbe93a9819301 Mon Sep 17 00:00:00 2001
From: Namjae Jeon <linkinjeon@kernel.org>
Date: Thu, 13 Jul 2023 21:59:37 +0900
Subject: [PATCH] exfat: check if filename entries exceeds max filename length
References: bsc#1214120 CVE-2023-4273
Git-commit: d42334578eba1390859012ebb91e1e556d51db49
Patch-mainline: v6.5-rc5
exfat_extract_uni_name copies characters from a given file name entry into
the 'uniname' variable. This variable is actually defined on the stack of
the exfat_readdir() function. According to the definition of
the 'exfat_uni_name' type, the file name should be limited 255 characters
(+ null teminator space), but the exfat_get_uniname_from_ext_entry()
function can write more characters because there is no check if filename
entries exceeds max filename length. This patch add the check not to copy
filename characters when exceeding max filename length.
Cc: stable@vger.kernel.org
Cc: Yuezhang Mo <Yuezhang.Mo@sony.com>
Reported-by: Maxim Suhanov <dfirblog@gmail.com>
Reviewed-by: Sungjong Seo <sj1557.seo@samsung.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Acked-by: David Disseldorp <ddiss@suse.de>
---
fs/exfat/dir.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/fs/exfat/dir.c b/fs/exfat/dir.c
index 7e856dc13dc7..b008c3e823ea 100644
--- a/fs/exfat/dir.c
+++ b/fs/exfat/dir.c
@@ -34,6 +34,7 @@ static void exfat_get_uniname_from_ext_entry(struct super_block *sb,
{
int i;
struct exfat_entry_set_cache *es;
+ unsigned int uni_len = 0, len;
es = exfat_get_dentry_set(sb, p_dir, entry, ES_ALL_ENTRIES);
if (!es)
@@ -52,7 +53,10 @@ static void exfat_get_uniname_from_ext_entry(struct super_block *sb,
if (exfat_get_entry_type(ep) != TYPE_EXTEND)
break;
- exfat_extract_uni_name(ep, uniname);
+ len = exfat_extract_uni_name(ep, uniname);
+ uni_len += len;
+ if (len != EXFAT_FILE_NAME_LEN || uni_len >= MAX_NAME_LENGTH)
+ break;
uniname += EXFAT_FILE_NAME_LEN;
}
@@ -1032,7 +1036,8 @@ int exfat_find_dir_entry(struct super_block *sb, struct exfat_inode_info *ei,
if (entry_type == TYPE_EXTEND) {
unsigned short entry_uniname[16], unichar;
- if (step != DIRENT_STEP_NAME) {
+ if (step != DIRENT_STEP_NAME ||
+ name_len >= MAX_NAME_LENGTH) {
step = DIRENT_STEP_FILE;
continue;
}
--
2.35.3