[PATCH AUTOSEL 5.10 04/24] ext2: Check block size validity during mount
STALE1252d
From: Sasha Levin <sashal@kernel.org>
Date: 2023-05-04 20:01:34
Also in:
lkml, stable
Subsystem:
ext2 file system, filesystems (vfs and infrastructure), the rest · Maintainers:
Jan Kara, Alexander Viro, Christian Brauner, Linus Torvalds
From: Jan Kara <jack@suse.cz> [ 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@syzkaller.appspotmail.com Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Sasha Levin <sashal@kernel.org> --- fs/ext2/ext2.h | 1 + fs/ext2/super.c | 7 +++++++ 2 files changed, 8 insertions(+)
diff --git a/fs/ext2/ext2.h b/fs/ext2/ext2.h
index 5136b7289e8da..f06367cfd7641 100644
--- a/fs/ext2/ext2.h
+++ b/fs/ext2/ext2.h@@ -177,6 +177,7 @@ 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 9a6475b2ab28b..ab01ec7ac48c5 100644
--- a/fs/ext2/super.c
+++ b/fs/ext2/super.c@@ -950,6 +950,13 @@ 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)) {
--
2.39.2