| Message ID | 0acc9d8cea160460e4bf049d761d285697b925bf.1688403622.git.fdmanana@suse.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | btrfs: fix error paths of btrfs_orphan_cleanup() | expand |
On Mon, Jul 03, 2023 at 06:15:31PM +0100, fdmanana@kernel.org wrote: > From: Filipe Manana <fdmanana@suse.com> > > At btrfs_orphan_cleanup(), if we can't find an inode (btrfs_iget() returns > an -ENOENT error pointer), we proceed with 'ret' set to -ENOENT and the > inode pointer set to ERR_PTR(-ENOENT). Later when we proceed to the body > of the following if statement: > > if (ret == -ENOENT || inode->i_nlink) { > (...) > trans = btrfs_start_transaction(root, 1); > if (IS_ERR(trans)) { > ret = PTR_ERR(trans); > iput(inode); > goto out; > } > (...) > ret = btrfs_del_orphan_item(trans, root, > found_key.objectid); > btrfs_end_transaction(trans); > if (ret) { > iput(inode); > goto out; > } > continue; > } > > If we get an error from btrfs_start_transaction() or from the call to > btrfs_del_orphan_item() we end calling iput() against an inode pointer > that has a value of ERR_PTR(-ENOENT), resulting in a crash with the > following trace: > > [438876.667234] BUG: kernel NULL pointer dereference, address: 0000000000000096 > [438876.667456] #PF: supervisor read access in kernel mode > [438876.667683] #PF: error_code(0x0000) - not-present page > [438876.667868] PGD 0 P4D 0 > [438876.668050] Oops: 0000 [#1] PREEMPT SMP PTI > [438876.668231] CPU: 0 PID: 2356187 Comm: mount Tainted: G W 6.4.0-rc6-btrfs-next-134+ #1 > [438876.668420] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.2-0-gea1b7a073390-prebuilt.qemu.org 04/01/2014 > [438876.668617] RIP: 0010:iput+0xa/0x20 > [438876.668818] Code: ff ff ff 66 (...) > [438876.669274] RSP: 0018:ffffafa9c0c9f9d0 EFLAGS: 00010282 > [438876.669512] RAX: ffffffffffffffe4 RBX: 000000000009453b RCX: 0000000000000000 > [438876.669746] RDX: 0000000000000001 RSI: ffffafa9c0c9f930 RDI: fffffffffffffffe > [438876.669989] RBP: ffff95c612f3b800 R08: 0000000000000001 R09: ffffffffffffffe4 > [438876.670231] R10: 00018f2a71010000 R11: 000000000ead96e3 R12: ffff95cb7d6909a0 > [438876.670476] R13: fffffffffffffffe R14: ffff95c60f477000 R15: 00000000ffffffe4 > [438876.670730] FS: 00007f5fbe30a840(0000) GS:ffff95ccdfa00000(0000) knlGS:0000000000000000 > [438876.670999] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [438876.671296] CR2: 0000000000000096 CR3: 000000055e9f6004 CR4: 0000000000370ef0 > [438876.671648] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > [438876.671984] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > [438876.672264] Call Trace: > [438876.744284] <TASK> > [438876.744589] ? __die_body+0x1b/0x60 > [438876.744872] ? page_fault_oops+0x15d/0x450 > [438876.745170] ? __kmem_cache_alloc_node+0x47/0x410 > [438876.745459] ? do_user_addr_fault+0x65/0x8a0 > [438876.745740] ? exc_page_fault+0x74/0x170 > [438876.746021] ? asm_exc_page_fault+0x22/0x30 > [438876.746305] ? iput+0xa/0x20 > [438876.746586] btrfs_orphan_cleanup+0x221/0x330 [btrfs] > [438876.746917] btrfs_lookup_dentry+0x58f/0x5f0 [btrfs] > [438876.747251] btrfs_lookup+0xe/0x30 [btrfs] > [438876.747564] __lookup_slow+0x82/0x130 > [438876.785817] walk_component+0xe5/0x160 > [438876.786129] path_lookupat.isra.0+0x6e/0x150 > [438876.786411] filename_lookup+0xcf/0x1a0 > [438876.786687] ? mod_objcg_state+0xd2/0x360 > [438876.786954] ? obj_cgroup_charge+0xf5/0x110 > [438876.787255] ? should_failslab+0xa/0x20 > [438876.787519] ? kmem_cache_alloc+0x47/0x450 > [438876.787772] vfs_path_lookup+0x51/0x90 > [438876.788023] mount_subtree+0x8d/0x130 > [438876.788306] btrfs_mount+0x149/0x410 [btrfs] > [438876.788624] ? __kmem_cache_alloc_node+0x47/0x410 > [438876.788899] ? vfs_parse_fs_param+0xc0/0x110 > [438876.789175] legacy_get_tree+0x24/0x50 > [438876.834144] vfs_get_tree+0x22/0xd0 > [438876.852406] path_mount+0x2d8/0x9c0 > [438876.852684] do_mount+0x79/0x90 > [438876.852914] __x64_sys_mount+0x8e/0xd0 > [438876.853135] do_syscall_64+0x38/0x90 > [438876.899182] entry_SYSCALL_64_after_hwframe+0x72/0xdc > [438876.958854] RIP: 0033:0x7f5fbe50b76a > [438876.959113] Code: 48 8b 0d a9 (...) > [438876.959578] RSP: 002b:00007fff01925798 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 > [438876.959808] RAX: ffffffffffffffda RBX: 00007f5fbe694264 RCX: 00007f5fbe50b76a > [438876.960026] RDX: 0000561bde6c8720 RSI: 0000561bde6bdec0 RDI: 0000561bde6c31a0 > [438876.960238] RBP: 0000561bde6bdc70 R08: 0000000000000000 R09: 0000000000000001 > [438876.960448] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 > [438876.960657] R13: 0000561bde6c31a0 R14: 0000561bde6c8720 R15: 0000561bde6bdc70 > [438876.960868] </TASK> > > So fix this by setting 'inode' to NULL whenever we get an error from > btrfs_iget(), and to make the code simpler, stop testing for 'ret' being > -ENOENT to check if we have an inode - instead test for 'inode' being NULL > or not. Having a NULL 'inode' prevents any iput() call from crashing, as > iput() ignores NULL inode pointers. Also, stop testing for a NULL return > value from btrfs_iget() with PTR_ERR_OR_ZERO(), because btrfs_iget() never > returns NULL - in case an inode is not found, it returns ERR_PTR(-ENOENT), > and in case of memory allocation failure, it returns ERR_PTR(-ENOMEM). > We also don't need the extra iput() calls on the error branches for the > btrfs_start_transaction() and btrfs_del_orphan_item() calls, as we have > already called iput() before, so remove them. > > Fixes: a13bb2c03848 ("btrfs: add missing iputs on orphan cleanup failure") > Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: Boris Burkov <boris@bur.io> > --- > fs/btrfs/inode.c | 20 ++++++++++---------- > 1 file changed, 10 insertions(+), 10 deletions(-) > > diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c > index d919318d2498..c8921589e2f3 100644 > --- a/fs/btrfs/inode.c > +++ b/fs/btrfs/inode.c > @@ -3659,11 +3659,14 @@ int btrfs_orphan_cleanup(struct btrfs_root *root) > found_key.type = BTRFS_INODE_ITEM_KEY; > found_key.offset = 0; > inode = btrfs_iget(fs_info->sb, last_objectid, root); > - ret = PTR_ERR_OR_ZERO(inode); > - if (ret && ret != -ENOENT) > - goto out; > + if (IS_ERR(inode)) { > + ret = PTR_ERR(inode); > + inode = NULL; > + if (ret != -ENOENT) > + goto out; > + } > > - if (ret == -ENOENT && root == fs_info->tree_root) { > + if (!inode && root == fs_info->tree_root) { > struct btrfs_root *dead_root; > int is_dead_root = 0; > > @@ -3724,8 +3727,8 @@ int btrfs_orphan_cleanup(struct btrfs_root *root) > * deleted but wasn't. The inode number may have been reused, > * but either way, we can delete the orphan item. > */ > - if (ret == -ENOENT || inode->i_nlink) { > - if (!ret) { > + if (!inode || inode->i_nlink) { > + if (inode) { > ret = btrfs_drop_verity_items(BTRFS_I(inode)); > iput(inode); > inode = NULL; > @@ -3735,7 +3738,6 @@ int btrfs_orphan_cleanup(struct btrfs_root *root) > trans = btrfs_start_transaction(root, 1); > if (IS_ERR(trans)) { > ret = PTR_ERR(trans); > - iput(inode); > goto out; > } > btrfs_debug(fs_info, "auto deleting %Lu", > @@ -3743,10 +3745,8 @@ int btrfs_orphan_cleanup(struct btrfs_root *root) > ret = btrfs_del_orphan_item(trans, root, > found_key.objectid); > btrfs_end_transaction(trans); > - if (ret) { > - iput(inode); > + if (ret) > goto out; > - } > continue; > } > > -- > 2.34.1 >
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index d919318d2498..c8921589e2f3 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -3659,11 +3659,14 @@ int btrfs_orphan_cleanup(struct btrfs_root *root) found_key.type = BTRFS_INODE_ITEM_KEY; found_key.offset = 0; inode = btrfs_iget(fs_info->sb, last_objectid, root); - ret = PTR_ERR_OR_ZERO(inode); - if (ret && ret != -ENOENT) - goto out; + if (IS_ERR(inode)) { + ret = PTR_ERR(inode); + inode = NULL; + if (ret != -ENOENT) + goto out; + } - if (ret == -ENOENT && root == fs_info->tree_root) { + if (!inode && root == fs_info->tree_root) { struct btrfs_root *dead_root; int is_dead_root = 0; @@ -3724,8 +3727,8 @@ int btrfs_orphan_cleanup(struct btrfs_root *root) * deleted but wasn't. The inode number may have been reused, * but either way, we can delete the orphan item. */ - if (ret == -ENOENT || inode->i_nlink) { - if (!ret) { + if (!inode || inode->i_nlink) { + if (inode) { ret = btrfs_drop_verity_items(BTRFS_I(inode)); iput(inode); inode = NULL; @@ -3735,7 +3738,6 @@ int btrfs_orphan_cleanup(struct btrfs_root *root) trans = btrfs_start_transaction(root, 1); if (IS_ERR(trans)) { ret = PTR_ERR(trans); - iput(inode); goto out; } btrfs_debug(fs_info, "auto deleting %Lu", @@ -3743,10 +3745,8 @@ int btrfs_orphan_cleanup(struct btrfs_root *root) ret = btrfs_del_orphan_item(trans, root, found_key.objectid); btrfs_end_transaction(trans); - if (ret) { - iput(inode); + if (ret) goto out; - } continue; }