From: Baokun Li Date: Fri, 5 May 2023 13:24:29 +0000 (+0800) Subject: ext4: check iomap type only if ext4_iomap_begin() does not fail X-Git-Url: http://git.hungrycats.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a27bc2b4a005dfe74be757900c5ef1d5604391ae;p=linux ext4: check iomap type only if ext4_iomap_begin() does not fail commit fa83c34e3e56b3c672af38059e066242655271b1 upstream. When ext4_iomap_overwrite_begin() calls ext4_iomap_begin() map blocks may fail for some reason (e.g. memory allocation failure, bare disk write), and later because "iomap->type ! = IOMAP_MAPPED" triggers WARN_ON(). When ext4 iomap_begin() returns an error, it is normal that the type of iomap->type may not match the expectation. Therefore, we only determine if iomap->type is as expected when ext4_iomap_begin() is executed successfully. Cc: stable@kernel.org Reported-by: syzbot+08106c4b7d60702dbc14@syzkaller.appspotmail.com Link: https://lore.kernel.org/all/00000000000015760b05f9b4eee9@google.com Signed-off-by: Baokun Li Reviewed-by: Jan Kara Link: https://lore.kernel.org/r/20230505132429.714648-1-libaokun1@huawei.com Signed-off-by: Theodore Ts'o Signed-off-by: Greg Kroah-Hartman --- diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index d66d54fb4f9f..bfbfec99b134 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -3577,7 +3577,7 @@ static int ext4_iomap_overwrite_begin(struct inode *inode, loff_t offset, */ flags &= ~IOMAP_WRITE; ret = ext4_iomap_begin(inode, offset, length, flags, iomap, srcmap); - WARN_ON_ONCE(iomap->type != IOMAP_MAPPED); + WARN_ON_ONCE(!ret && iomap->type != IOMAP_MAPPED); return ret; }