4eb1f66dce
We've got bug reports that btrfs crashes when quota is enabled on 32bit kernel, typically with the Oops like below: BUG: unable to handle kernel NULL pointer dereference at 00000004 IP: [<f9234590>] find_parent_nodes+0x360/0x1380 [btrfs] *pde = 00000000 Oops: 0000 [#1] SMP CPU: 0 PID: 151 Comm: kworker/u8:2 Tainted: G S W 3.15.2-1.gd43d97e-default #1 Workqueue: btrfs-qgroup-rescan normal_work_helper [btrfs] task: f1478130 ti: f147c000 task.ti: f147c000 EIP: 0060:[<f9234590>] EFLAGS: 00010213 CPU: 0 EIP is at find_parent_nodes+0x360/0x1380 [btrfs] EAX: f147dda8 EBX: f147ddb0 ECX: 00000011 EDX: 00000000 ESI: 00000000 EDI: f147dda4 EBP: f147ddf8 ESP: f147dd38 DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068 CR0: 8005003b CR2: 00000004 CR3: 00bf3000 CR4: 00000690 Stack: 00000000 00000000 f147dda4 00000050 00000001 00000000 00000001 00000050 00000001 00000000 d3059000 00000001 00000022 000000a8 00000000 00000000 00000000 000000a1 00000000 00000000 00000001 00000000 00000000 11800000 Call Trace: [<f923564d>] __btrfs_find_all_roots+0x9d/0xf0 [btrfs] [<f9237bb1>] btrfs_qgroup_rescan_worker+0x401/0x760 [btrfs] [<f9206148>] normal_work_helper+0xc8/0x270 [btrfs] [<c025e38b>] process_one_work+0x11b/0x390 [<c025eea1>] worker_thread+0x101/0x340 [<c026432b>] kthread+0x9b/0xb0 [<c0712a71>] ret_from_kernel_thread+0x21/0x30 [<c0264290>] kthread_create_on_node+0x110/0x110 This indicates a NULL corruption in prefs_delayed list. The further investigation and bisection pointed that the call of ulist_add_merge() results in the corruption. ulist_add_merge() takes u64 as aux and writes a 64bit value into old_aux. The callers of this function in backref.c, however, pass a pointer of a pointer to old_aux. That is, the function overwrites 64bit value on 32bit pointer. This caused a NULL in the adjacent variable, in this case, prefs_delayed. Here is a quick attempt to band-aid over this: a new function, ulist_add_merge_ptr() is introduced to pass/store properly a pointer value instead of u64. There are still ugly void ** cast remaining in the callers because void ** cannot be taken implicitly. But, it's safer than explicit cast to u64, anyway. Bugzilla: https://bugzilla.novell.com/show_bug.cgi?id=887046 Cc: <stable@vger.kernel.org> [v3.11+] Signed-off-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Chris Mason <clm@fb.com>
80 lines
2 KiB
C
80 lines
2 KiB
C
/*
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* Copyright (C) 2011 STRATO AG
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* written by Arne Jansen <sensille@gmx.net>
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* Distributed under the GNU GPL license version 2.
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*
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*/
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#ifndef __ULIST__
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#define __ULIST__
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#include <linux/list.h>
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#include <linux/rbtree.h>
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/*
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* ulist is a generic data structure to hold a collection of unique u64
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* values. The only operations it supports is adding to the list and
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* enumerating it.
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* It is possible to store an auxiliary value along with the key.
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*
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*/
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struct ulist_iterator {
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#ifdef CONFIG_BTRFS_DEBUG
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int i;
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#endif
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struct list_head *cur_list; /* hint to start search */
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};
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/*
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* element of the list
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*/
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struct ulist_node {
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u64 val; /* value to store */
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u64 aux; /* auxiliary value saved along with the val */
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#ifdef CONFIG_BTRFS_DEBUG
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int seqnum; /* sequence number this node is added */
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#endif
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struct list_head list; /* used to link node */
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struct rb_node rb_node; /* used to speed up search */
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};
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struct ulist {
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/*
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* number of elements stored in list
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*/
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unsigned long nnodes;
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struct list_head nodes;
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struct rb_root root;
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};
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void ulist_init(struct ulist *ulist);
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void ulist_reinit(struct ulist *ulist);
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struct ulist *ulist_alloc(gfp_t gfp_mask);
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void ulist_free(struct ulist *ulist);
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int ulist_add(struct ulist *ulist, u64 val, u64 aux, gfp_t gfp_mask);
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int ulist_add_merge(struct ulist *ulist, u64 val, u64 aux,
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u64 *old_aux, gfp_t gfp_mask);
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/* just like ulist_add_merge() but take a pointer for the aux data */
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static inline int ulist_add_merge_ptr(struct ulist *ulist, u64 val, void *aux,
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void **old_aux, gfp_t gfp_mask)
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{
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#if BITS_PER_LONG == 32
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u64 old64 = (uintptr_t)*old_aux;
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int ret = ulist_add_merge(ulist, val, (uintptr_t)aux, &old64, gfp_mask);
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*old_aux = (void *)((uintptr_t)old64);
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return ret;
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#else
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return ulist_add_merge(ulist, val, (u64)aux, (u64 *)old_aux, gfp_mask);
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#endif
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}
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struct ulist_node *ulist_next(struct ulist *ulist,
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struct ulist_iterator *uiter);
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#define ULIST_ITER_INIT(uiter) ((uiter)->cur_list = NULL)
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#endif
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