Commit 8a143588 authored by Rabin Vincent's avatar Rabin Vincent Committed by Richard Weinberger

ubi: fastmap: Fix slab corruption

Booting with UBI fastmap and SLUB debugging enabled results in the
following splats.  The problem is that ubi_scan_fastmap() moves the
fastmap blocks from the scan_ai (allocated in scan_fast()) to the ai
allocated in ubi_attach().  This results in two problems:

 - When the scan_ai is freed, aebs which were allocated from its slab
   cache are still in use.

 - When the other ai is being destroyed in destroy_ai(), the
   arguments to kmem_cache_free() call are incorrect since aebs on its
   ->fastmap list were allocated with a slab cache from a differnt ai.

Fix this by making a copy of the aebs in ubi_scan_fastmap() instead of
moving them.

 =============================================================================
 BUG ubi_aeb_slab_cache (Not tainted): Objects remaining in ubi_aeb_slab_cache on __kmem_cache_shutdown()
 -----------------------------------------------------------------------------

 INFO: Slab 0xbfd2da3c objects=17 used=1 fp=0xb33d7748 flags=0x40000080
 CPU: 1 PID: 118 Comm: ubiattach Tainted: G    B           4.9.15 #3
 [<80111910>] (unwind_backtrace) from [<8010d498>] (show_stack+0x18/0x1c)
 [<8010d498>] (show_stack) from [<804a3274>] (dump_stack+0xb4/0xe0)
 [<804a3274>] (dump_stack) from [<8026c47c>] (slab_err+0x78/0x88)
 [<8026c47c>] (slab_err) from [<802735bc>] (__kmem_cache_shutdown+0x180/0x3e0)
 [<802735bc>] (__kmem_cache_shutdown) from [<8024e13c>] (shutdown_cache+0x1c/0x60)
 [<8024e13c>] (shutdown_cache) from [<8024ed64>] (kmem_cache_destroy+0x19c/0x20c)
 [<8024ed64>] (kmem_cache_destroy) from [<8057cc14>] (destroy_ai+0x1dc/0x1e8)
 [<8057cc14>] (destroy_ai) from [<8057f04c>] (ubi_attach+0x3f4/0x450)
 [<8057f04c>] (ubi_attach) from [<8056fe70>] (ubi_attach_mtd_dev+0x60c/0xff8)
 [<8056fe70>] (ubi_attach_mtd_dev) from [<80571d78>] (ctrl_cdev_ioctl+0x110/0x2b8)
 [<80571d78>] (ctrl_cdev_ioctl) from [<8029c77c>] (do_vfs_ioctl+0xac/0xa00)
 [<8029c77c>] (do_vfs_ioctl) from [<8029d10c>] (SyS_ioctl+0x3c/0x64)
 [<8029d10c>] (SyS_ioctl) from [<80108860>] (ret_fast_syscall+0x0/0x1c)
 INFO: Object 0xb33d7e88 @offset=3720
 INFO: Allocated in scan_peb+0x608/0x81c age=72 cpu=1 pid=118
 	kmem_cache_alloc+0x3b0/0x43c
 	scan_peb+0x608/0x81c
 	ubi_attach+0x124/0x450
 	ubi_attach_mtd_dev+0x60c/0xff8
 	ctrl_cdev_ioctl+0x110/0x2b8
 	do_vfs_ioctl+0xac/0xa00
 	SyS_ioctl+0x3c/0x64
 	ret_fast_syscall+0x0/0x1c
 kmem_cache_destroy ubi_aeb_slab_cache: Slab cache still has objects
 CPU: 1 PID: 118 Comm: ubiattach Tainted: G    B           4.9.15 #3
 [<80111910>] (unwind_backtrace) from [<8010d498>] (show_stack+0x18/0x1c)
 [<8010d498>] (show_stack) from [<804a3274>] (dump_stack+0xb4/0xe0)
 [<804a3274>] (dump_stack) from [<8024ed80>] (kmem_cache_destroy+0x1b8/0x20c)
 [<8024ed80>] (kmem_cache_destroy) from [<8057cc14>] (destroy_ai+0x1dc/0x1e8)
 [<8057cc14>] (destroy_ai) from [<8057f04c>] (ubi_attach+0x3f4/0x450)
 [<8057f04c>] (ubi_attach) from [<8056fe70>] (ubi_attach_mtd_dev+0x60c/0xff8)
 [<8056fe70>] (ubi_attach_mtd_dev) from [<80571d78>] (ctrl_cdev_ioctl+0x110/0x2b8)
 [<80571d78>] (ctrl_cdev_ioctl) from [<8029c77c>] (do_vfs_ioctl+0xac/0xa00)
 [<8029c77c>] (do_vfs_ioctl) from [<8029d10c>] (SyS_ioctl+0x3c/0x64)
 [<8029d10c>] (SyS_ioctl) from [<80108860>] (ret_fast_syscall+0x0/0x1c)
 cache_from_obj: Wrong slab cache. ubi_aeb_slab_cache but object is from ubi_aeb_slab_cache
 ------------[ cut here ]------------
 WARNING: CPU: 1 PID: 118 at mm/slab.h:354 kmem_cache_free+0x39c/0x450
 Modules linked in:
 CPU: 1 PID: 118 Comm: ubiattach Tainted: G    B           4.9.15 #3
 [<80111910>] (unwind_backtrace) from [<8010d498>] (show_stack+0x18/0x1c)
 [<8010d498>] (show_stack) from [<804a3274>] (dump_stack+0xb4/0xe0)
 [<804a3274>] (dump_stack) from [<80120e40>] (__warn+0xf4/0x10c)
 [<80120e40>] (__warn) from [<80120f20>] (warn_slowpath_null+0x28/0x30)
 [<80120f20>] (warn_slowpath_null) from [<80271fe0>] (kmem_cache_free+0x39c/0x450)
 [<80271fe0>] (kmem_cache_free) from [<8057cb88>] (destroy_ai+0x150/0x1e8)
 [<8057cb88>] (destroy_ai) from [<8057ef1c>] (ubi_attach+0x2c4/0x450)
 [<8057ef1c>] (ubi_attach) from [<8056fe70>] (ubi_attach_mtd_dev+0x60c/0xff8)
 [<8056fe70>] (ubi_attach_mtd_dev) from [<80571d78>] (ctrl_cdev_ioctl+0x110/0x2b8)
 [<80571d78>] (ctrl_cdev_ioctl) from [<8029c77c>] (do_vfs_ioctl+0xac/0xa00)
 [<8029c77c>] (do_vfs_ioctl) from [<8029d10c>] (SyS_ioctl+0x3c/0x64)
 [<8029d10c>] (SyS_ioctl) from [<80108860>] (ret_fast_syscall+0x0/0x1c)
 ---[ end trace 2bd8396277fd0a0b ]---
 =============================================================================
 BUG ubi_aeb_slab_cache (Tainted: G    B   W      ): page slab pointer corrupt.
 -----------------------------------------------------------------------------

 INFO: Allocated in scan_peb+0x608/0x81c age=104 cpu=1 pid=118
 	kmem_cache_alloc+0x3b0/0x43c
 	scan_peb+0x608/0x81c
 	ubi_attach+0x124/0x450
 	ubi_attach_mtd_dev+0x60c/0xff8
 	ctrl_cdev_ioctl+0x110/0x2b8
 	do_vfs_ioctl+0xac/0xa00
 	SyS_ioctl+0x3c/0x64
 	ret_fast_syscall+0x0/0x1c
 INFO: Slab 0xbfd2da3c objects=17 used=1 fp=0xb33d7748 flags=0x40000081
 INFO: Object 0xb33d7e88 @offset=3720 fp=0xb33d7da0

 Redzone b33d7e80: cc cc cc cc cc cc cc cc                          ........
 Object b33d7e88: 02 00 00 00 01 00 00 00 00 f0 ff 7f ff ff ff ff  ................
 Object b33d7e98: 00 00 00 00 00 00 00 00 bd 16 00 00 00 00 00 00  ................
 Object b33d7ea8: 00 01 00 00 00 02 00 00 00 00 00 00 00 00 00 00  ................
 Redzone b33d7eb8: cc cc cc cc                                      ....
 Padding b33d7f60: 5a 5a 5a 5a 5a 5a 5a 5a                          ZZZZZZZZ
 CPU: 1 PID: 118 Comm: ubiattach Tainted: G    B   W       4.9.15 #3
 [<80111910>] (unwind_backtrace) from [<8010d498>] (show_stack+0x18/0x1c)
 [<8010d498>] (show_stack) from [<804a3274>] (dump_stack+0xb4/0xe0)
 [<804a3274>] (dump_stack) from [<80271770>] (free_debug_processing+0x320/0x3c4)
 [<80271770>] (free_debug_processing) from [<80271ad0>] (__slab_free+0x2bc/0x430)
 [<80271ad0>] (__slab_free) from [<80272024>] (kmem_cache_free+0x3e0/0x450)
 [<80272024>] (kmem_cache_free) from [<8057cb88>] (destroy_ai+0x150/0x1e8)
 [<8057cb88>] (destroy_ai) from [<8057ef1c>] (ubi_attach+0x2c4/0x450)
 [<8057ef1c>] (ubi_attach) from [<8056fe70>] (ubi_attach_mtd_dev+0x60c/0xff8)
 [<8056fe70>] (ubi_attach_mtd_dev) from [<80571d78>] (ctrl_cdev_ioctl+0x110/0x2b8)
 [<80571d78>] (ctrl_cdev_ioctl) from [<8029c77c>] (do_vfs_ioctl+0xac/0xa00)
 [<8029c77c>] (do_vfs_ioctl) from [<8029d10c>] (SyS_ioctl+0x3c/0x64)
 [<8029d10c>] (SyS_ioctl) from [<80108860>] (ret_fast_syscall+0x0/0x1c)
 FIX ubi_aeb_slab_cache: Object at 0xb33d7e88 not freed
Signed-off-by: default avatarRabin Vincent <rabinv@axis.com>
Signed-off-by: default avatarRichard Weinberger <richard@nod.at>
parent 8326c1ee
......@@ -828,6 +828,24 @@ static int find_fm_anchor(struct ubi_attach_info *ai)
return ret;
}
static struct ubi_ainf_peb *clone_aeb(struct ubi_attach_info *ai,
struct ubi_ainf_peb *old)
{
struct ubi_ainf_peb *new;
new = ubi_alloc_aeb(ai, old->pnum, old->ec);
if (!new)
return NULL;
new->vol_id = old->vol_id;
new->sqnum = old->sqnum;
new->lnum = old->lnum;
new->scrub = old->scrub;
new->copy_flag = old->copy_flag;
return new;
}
/**
* ubi_scan_fastmap - scan the fastmap.
* @ubi: UBI device object
......@@ -847,7 +865,7 @@ int ubi_scan_fastmap(struct ubi_device *ubi, struct ubi_attach_info *ai,
struct ubi_vid_hdr *vh;
struct ubi_ec_hdr *ech;
struct ubi_fastmap_layout *fm;
struct ubi_ainf_peb *tmp_aeb, *aeb;
struct ubi_ainf_peb *aeb;
int i, used_blocks, pnum, fm_anchor, ret = 0;
size_t fm_size;
__be32 crc, tmp_crc;
......@@ -857,9 +875,16 @@ int ubi_scan_fastmap(struct ubi_device *ubi, struct ubi_attach_info *ai,
if (fm_anchor < 0)
return UBI_NO_FASTMAP;
/* Move all (possible) fastmap blocks into our new attach structure. */
list_for_each_entry_safe(aeb, tmp_aeb, &scan_ai->fastmap, u.list)
list_move_tail(&aeb->u.list, &ai->fastmap);
/* Copy all (possible) fastmap blocks into our new attach structure. */
list_for_each_entry(aeb, &scan_ai->fastmap, u.list) {
struct ubi_ainf_peb *new;
new = clone_aeb(ai, aeb);
if (!new)
return -ENOMEM;
list_add(&new->u.list, &ai->fastmap);
}
down_write(&ubi->fm_protect);
memset(ubi->fm_buf, 0, ubi->fm_size);
......
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