From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 699EB267F5B; Tue, 8 Apr 2025 11:46:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744112780; cv=none; b=PS49fVkhCBRKk8aV3B6S2lqH78J5hMKkwCQnuytyY+5m6+0IAlyQkkvQ6tZls8/BYLb3ReiuIHk3iQxE+KVDDO6smapEK+PQR/zn7qg3vbofdXCr4Bzp7SgJ8ZVBqJhfdjdZeqhx+iPlCYkJRKfuONQ87hwE6B53nNsWBjUjHA0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744112780; c=relaxed/simple; bh=eGewagAdoXJTfbeT9DxZEDJQywXQd0rUlxKxxLEPWAc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=BwmlidwXXDlyeqswLwcPLL8mpHEH3cIAmk2JmAuG5ReHeG1TszrYcoOeSteC7Nb87i5QGfkD26YOlsDcJ4i951e/qXbFAEdNamvThz1OXI/cCr+WIVBprRwqmiOg7043ttc9onEFD9pJ9ihQ0VLIXj5/UMlXijdT5sDdmZNpisU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=vPUbvTJl; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="vPUbvTJl" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EDC8DC4CEE5; Tue, 8 Apr 2025 11:46:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1744112780; bh=eGewagAdoXJTfbeT9DxZEDJQywXQd0rUlxKxxLEPWAc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=vPUbvTJlYt8RwlR66yGdeXzmdgYDleo1+OmVdHeLxuumuRA/0UuVyAi5Rk8YHxVmf fkyn+MROBs50GhGDHOsdCi6NNeQ/5ac5k+LfR3NgaZfw9hA5xudIkN812tpTh+w+xc ma7TU+mfyjJJfDJXWHu/7NIgPB/MGYgB+ccfzMwM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot , Qasim Ijaz , Jan Kara , Sasha Levin Subject: [PATCH 5.15 194/279] isofs: fix KMSAN uninit-value bug in do_isofs_readdir() Date: Tue, 8 Apr 2025 12:49:37 +0200 Message-ID: <20250408104831.572130281@linuxfoundation.org> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250408104826.319283234@linuxfoundation.org> References: <20250408104826.319283234@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Qasim Ijaz [ Upstream commit 81a82e8f33880793029cd6f8a766fb13b737e6a7 ] In do_isofs_readdir() when assigning the variable "struct iso_directory_record *de" the b_data field of the buffer_head is accessed and an offset is added to it, the size of b_data is 2048 and the offset size is 2047, meaning "de = (struct iso_directory_record *) (bh->b_data + offset);" yields the final byte of the 2048 sized b_data block. The first byte of the directory record (de_len) is then read and found to be 31, meaning the directory record size is 31 bytes long. The directory record is defined by the structure: struct iso_directory_record { __u8 length; // 1 byte __u8 ext_attr_length; // 1 byte __u8 extent[8]; // 8 bytes __u8 size[8]; // 8 bytes __u8 date[7]; // 7 bytes __u8 flags; // 1 byte __u8 file_unit_size; // 1 byte __u8 interleave; // 1 byte __u8 volume_sequence_number[4]; // 4 bytes __u8 name_len; // 1 byte char name[]; // variable size } __attribute__((packed)); The fixed portion of this structure occupies 33 bytes. Therefore, a valid directory record must be at least 33 bytes long (even without considering the variable-length name field). Since de_len is only 31, it is insufficient to contain the complete fixed header. The code later hits the following sanity check that compares de_len against the sum of de->name_len and sizeof(struct iso_directory_record): if (de_len < de->name_len[0] + sizeof(struct iso_directory_record)) { ... } Since the fixed portion of the structure is 33 bytes (up to and including name_len member), a valid record should have de_len of at least 33 bytes; here, however, de_len is too short, and the field de->name_len (located at offset 32) is accessed even though it lies beyond the available 31 bytes. This access on the corrupted isofs data triggers a KASAN uninitialized memory warning. The fix would be to first verify that de_len is at least sizeof(struct iso_directory_record) before accessing any fields like de->name_len. Reported-by: syzbot Tested-by: syzbot Closes: https://syzkaller.appspot.com/bug?extid=812641c6c3d7586a1613 Fixes: 2deb1acc653c ("isofs: fix access to unallocated memory when reading corrupted filesystem") Signed-off-by: Qasim Ijaz Signed-off-by: Jan Kara Link: https://patch.msgid.link/20250211195900.42406-1-qasdev00@gmail.com Signed-off-by: Sasha Levin --- fs/isofs/dir.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/isofs/dir.c b/fs/isofs/dir.c index eb2f8273e6f15..09df40b612fbf 100644 --- a/fs/isofs/dir.c +++ b/fs/isofs/dir.c @@ -147,7 +147,8 @@ static int do_isofs_readdir(struct inode *inode, struct file *file, de = tmpde; } /* Basic sanity check, whether name doesn't exceed dir entry */ - if (de_len < de->name_len[0] + + if (de_len < sizeof(struct iso_directory_record) || + de_len < de->name_len[0] + sizeof(struct iso_directory_record)) { printk(KERN_NOTICE "iso9660: Corrupted directory entry" " in block %lu of inode %lu\n", block, -- 2.39.5