This is a note to let you know that I've just added the patch titled
ext2: Check block size validity during mount
to the 6.3-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ext2-check-block-size-validity-during-mount.patch
and it can be found in the queue-6.3 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit ef413deb612a9017b7171357be844d08682f4521
Author: Jan Kara <jack@xxxxxxx>
Date: Wed Mar 1 11:59:39 2023 +0100
ext2: Check block size validity during mount
[ Upstream commit 62aeb94433fcec80241754b70d0d1836d5926b0a ]
Check that log of block size stored in the superblock has sensible
value. Otherwise the shift computing the block size can overflow leading
to undefined behavior.
Reported-by: syzbot+4fec412f59eba8c01b77@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Jan Kara <jack@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/ext2/ext2.h b/fs/ext2/ext2.h
index cb78d7dcfb952..c60cb900bb2f4 100644
--- a/fs/ext2/ext2.h
+++ b/fs/ext2/ext2.h
@@ -180,6 +180,7 @@ static inline struct ext2_sb_info *EXT2_SB(struct super_block *sb)
#define EXT2_MIN_BLOCK_SIZE 1024
#define EXT2_MAX_BLOCK_SIZE 4096
#define EXT2_MIN_BLOCK_LOG_SIZE 10
+#define EXT2_MAX_BLOCK_LOG_SIZE 16
#define EXT2_BLOCK_SIZE(s) ((s)->s_blocksize)
#define EXT2_ADDR_PER_BLOCK(s) (EXT2_BLOCK_SIZE(s) / sizeof (__u32))
#define EXT2_BLOCK_SIZE_BITS(s) ((s)->s_blocksize_bits)
diff --git a/fs/ext2/super.c b/fs/ext2/super.c
index 69c88facfe90e..f342f347a695f 100644
--- a/fs/ext2/super.c
+++ b/fs/ext2/super.c
@@ -945,6 +945,13 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent)
goto failed_mount;
}
+ if (le32_to_cpu(es->s_log_block_size) >
+ (EXT2_MAX_BLOCK_LOG_SIZE - BLOCK_SIZE_BITS)) {
+ ext2_msg(sb, KERN_ERR,
+ "Invalid log block size: %u",
+ le32_to_cpu(es->s_log_block_size));
+ goto failed_mount;
+ }
blocksize = BLOCK_SIZE << le32_to_cpu(sbi->s_es->s_log_block_size);
if (test_opt(sb, DAX)) {
