From e500902cd5b88fd805d2c206bcce4f9782cc8cd4 Mon Sep 17 00:00:00 2001 From: "zhangyi (F)" Date: Thu, 24 Sep 2020 15:33:31 +0800 Subject: [PATCH] ext4: clear buffer verified flag if read meta block from disk commit d9befedaafcf3a111428baa7c45b02923eab2d87 upstream. The metadata buffer is no longer trusted after we read it from disk again because it is not uptodate for some reasons (e.g. failed to write back). Otherwise we may get below memory corruption problem in ext4_ext_split()->memset() if we read stale data from the newly allocated extent block on disk which has been failed to async write out but miss verify again since the verified bit has already been set on the buffer. [ 29.774674] BUG: unable to handle kernel paging request at ffff88841949d000 ... [ 29.783317] Oops: 0002 [#2] SMP [ 29.784219] R10: 00000000000f4240 R11: 0000000000002e28 R12: ffff88842fa1c800 [ 29.784627] CPU: 1 PID: 126 Comm: kworker/u4:3 Tainted: G D W [ 29.785546] R13: ffffffff9cddcc20 R14: ffffffff9cddd420 R15: ffff88842fa1c2f8 [ 29.786679] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),BIOS ?-20190727_0738364 [ 29.787588] FS: 0000000000000000(0000) GS:ffff88842fa00000(0000) knlGS:0000000000000000 [ 29.789288] Workqueue: writeback wb_workfn [ 29.790319] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 29.790321] (flush-8:0) [ 29.790844] CR2: 0000000000000008 CR3: 00000004234f2000 CR4: 00000000000006f0 [ 29.791924] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 29.792839] RIP: 0010:__memset+0x24/0x30 [ 29.793739] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 29.794256] Code: 90 90 90 90 90 90 0f 1f 44 00 00 49 89 f9 48 89 d1 83 e2 07 48 c1 e9 033 [ 29.795161] Kernel panic - not syncing: Fatal exception in interrupt ... [ 29.808149] Call Trace: [ 29.808475] ext4_ext_insert_extent+0x102e/0x1be0 [ 29.809085] ext4_ext_map_blocks+0xa89/0x1bb0 [ 29.809652] ext4_map_blocks+0x290/0x8a0 [ 29.809085] ext4_ext_map_blocks+0xa89/0x1bb0 [ 29.809652] ext4_map_blocks+0x290/0x8a0 [ 29.810161] ext4_writepages+0xc85/0x17c0 ... Fix this by clearing buffer's verified bit if we read meta block from disk again. Signed-off-by: zhangyi (F) Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20200924073337.861472-2-yi.zhang@huawei.com Signed-off-by: Theodore Ts'o Signed-off-by: Greg Kroah-Hartman --- fs/ext4/balloc.c | 1 + fs/ext4/extents.c | 1 + fs/ext4/ialloc.c | 1 + fs/ext4/inode.c | 5 ++++- fs/ext4/super.c | 1 + 5 files changed, 8 insertions(+), 1 deletion(-) diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c index 48c3df47748dbe..8e7e9715cde9c9 100644 --- a/fs/ext4/balloc.c +++ b/fs/ext4/balloc.c @@ -494,6 +494,7 @@ ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group, * submit the buffer_head for reading */ set_buffer_new(bh); + clear_buffer_verified(bh); trace_ext4_read_block_bitmap_load(sb, block_group, ignore_locked); bh->b_end_io = ext4_end_bitmap_read; get_bh(bh); diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index a0481582187a35..0a5205edc00a8f 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -501,6 +501,7 @@ __read_extent_tree_block(const char *function, unsigned int line, if (!bh_uptodate_or_lock(bh)) { trace_ext4_ext_load_extent(inode, pblk, _RET_IP_); + clear_buffer_verified(bh); err = bh_submit_read(bh); if (err < 0) goto errout; diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c index df25d38d65393e..20cda952c62198 100644 --- a/fs/ext4/ialloc.c +++ b/fs/ext4/ialloc.c @@ -188,6 +188,7 @@ ext4_read_inode_bitmap(struct super_block *sb, ext4_group_t block_group) /* * submit the buffer_head for reading */ + clear_buffer_verified(bh); trace_ext4_load_inode_bitmap(sb, block_group); bh->b_end_io = ext4_end_bitmap_read; get_bh(bh); diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index bbe95498f8f2dc..288704e9064b35 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -884,6 +884,7 @@ struct buffer_head *ext4_bread(handle_t *handle, struct inode *inode, return bh; if (!bh || ext4_buffer_uptodate(bh)) return bh; + clear_buffer_verified(bh); ll_rw_block(REQ_OP_READ, REQ_META | REQ_PRIO, 1, &bh); wait_on_buffer(bh); if (buffer_uptodate(bh)) @@ -909,9 +910,11 @@ int ext4_bread_batch(struct inode *inode, ext4_lblk_t block, int bh_count, for (i = 0; i < bh_count; i++) /* Note that NULL bhs[i] is valid because of holes. */ - if (bhs[i] && !ext4_buffer_uptodate(bhs[i])) + if (bhs[i] && !ext4_buffer_uptodate(bhs[i])) { + clear_buffer_verified(bhs[i]); ll_rw_block(REQ_OP_READ, REQ_META | REQ_PRIO, 1, &bhs[i]); + } if (!wait) return 0; diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 76291cd879a373..265c75256989e2 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -156,6 +156,7 @@ ext4_sb_bread(struct super_block *sb, sector_t block, int op_flags) return ERR_PTR(-ENOMEM); if (ext4_buffer_uptodate(bh)) return bh; + clear_buffer_verified(bh); ll_rw_block(REQ_OP_READ, REQ_META | op_flags, 1, &bh); wait_on_buffer(bh); if (buffer_uptodate(bh))