From: Hou Tao houtao1@huawei.com
commit a2c2f0826e2b75560b31daf1cd9a755ab93cf4c6 upstream.
Now EXT4_FC_TAG_ADD_RANGE uses ext4_extent to track the newly-added blocks, but the limit on the max value of ee_len field is ignored, and it can lead to BUG_ON as shown below when running command "fallocate -l 128M file" on a fast_commit-enabled fs:
kernel BUG at fs/ext4/ext4_extents.h:199! invalid opcode: 0000 [#1] SMP PTI CPU: 3 PID: 624 Comm: fallocate Not tainted 5.14.0-rc6+ #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) RIP: 0010:ext4_fc_write_inode_data+0x1f3/0x200 Call Trace: ? ext4_fc_write_inode+0xf2/0x150 ext4_fc_commit+0x93b/0xa00 ? ext4_fallocate+0x1ad/0x10d0 ext4_sync_file+0x157/0x340 ? ext4_sync_file+0x157/0x340 vfs_fsync_range+0x49/0x80 do_fsync+0x3d/0x70 __x64_sys_fsync+0x14/0x20 do_syscall_64+0x3b/0xc0 entry_SYSCALL_64_after_hwframe+0x44/0xae
Simply fixing it by limiting the number of blocks in one EXT4_FC_TAG_ADD_RANGE TLV.
Fixes: aa75f4d3daae ("ext4: main fast-commit commit path") Cc: stable@kernel.org Signed-off-by: Hou Tao houtao1@huawei.com Signed-off-by: Theodore Ts'o tytso@mit.edu Link: https://lore.kernel.org/r/20210820044505.474318-1-houtao1@huawei.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/ext4/fast_commit.c | 6 ++++++ 1 file changed, 6 insertions(+)
--- a/fs/ext4/fast_commit.c +++ b/fs/ext4/fast_commit.c @@ -832,6 +832,12 @@ static int ext4_fc_write_inode_data(stru sizeof(lrange), (u8 *)&lrange, crc)) return -ENOSPC; } else { + unsigned int max = (map.m_flags & EXT4_MAP_UNWRITTEN) ? + EXT_UNWRITTEN_MAX_LEN : EXT_INIT_MAX_LEN; + + /* Limit the number of blocks in one extent */ + map.m_len = min(max, map.m_len); + fc_ext.fc_ino = cpu_to_le32(inode->i_ino); ex = (struct ext4_extent *)&fc_ext.fc_ex; ex->ee_block = cpu_to_le32(map.m_lblk);