From: Jan Kara Date: Wed, 1 Mar 2023 10:59:39 +0000 (+0100) Subject: ext2: Check block size validity during mount X-Git-Tag: v4.14.316~72 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0ebfaf14150f55550cffb1148ed3920143c7a69c;p=thirdparty%2Fkernel%2Fstable.git 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@syzkaller.appspotmail.com Signed-off-by: Jan Kara Signed-off-by: Sasha Levin --- diff --git a/fs/ext2/ext2.h b/fs/ext2/ext2.h index 032295e1d3865..b500fed96a692 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 5f7079b65426c..7ca9fb0bfc324 100644 --- a/fs/ext2/super.c +++ b/fs/ext2/super.c @@ -965,6 +965,13 @@ 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 (sbi->s_mount_opt & EXT2_MOUNT_DAX) {