From c2fdf827f8fc6a571e1b7cc38a61041f0321adf5 Mon Sep 17 00:00:00 2001 From: Namjae Jeon Date: Thu, 13 Jul 2023 21:59:37 +0900 Subject: [PATCH] exfat: check if filename entries exceeds max filename length [ 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 Reported-by: Maxim Suhanov Reviewed-by: Sungjong Seo Signed-off-by: Namjae Jeon Signed-off-by: Sasha Levin --- 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 78de6f67f882..51b03b0dd5f7 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; } @@ -1024,7 +1028,8 @@ 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; }