From: Namjae Jeon linkinjeon@kernel.org

stable inclusion from stable-v5.10.190 commit 381f7df0f3c3bd7dceb3e2b2b64c2f6247e2ac19 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I7TLII CVE: CVE-2023-4273

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

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[ Upstream commit d42334578eba1390859012ebb91e1e556d51db49 ]

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 Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: ZhaoLong Wang wangzhaolong1@huawei.com --- 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 dedbc55cd48f..0d736bf97146 100644 --- a/fs/exfat/dir.c +++ b/fs/exfat/dir.c @@ -33,6 +33,7 @@ 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) @@ -51,7 +52,10 @@ 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; }

@@ -1026,7 +1030,8 @@ 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; }