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Subject[PATCH 3/5] f2fs: fix to do sanity check with i_extra_isize
Date
From: Chao Yu <yuchao0@huawei.com>

If inode.i_extra_isize was fuzzed to an abnormal value, when
calculating inline data size, the result will overflow, result
in accessing invalid memory area when operating inline data.

Let's do sanity check with i_extra_isize during inode loading
for fixing.

https://bugzilla.kernel.org/show_bug.cgi?id=200421

- Reproduce

- POC (poc.c)
#define _GNU_SOURCE
#include <sys/types.h>
#include <sys/mount.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/xattr.h>

#include <dirent.h>
#include <errno.h>
#include <error.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <linux/falloc.h>
#include <linux/loop.h>

static void activity(char *mpoint) {

char *foo_bar_baz;
char *foo_baz;
char *xattr;
int err;

err = asprintf(&foo_bar_baz, "%s/foo/bar/baz", mpoint);
err = asprintf(&foo_baz, "%s/foo/baz", mpoint);
err = asprintf(&xattr, "%s/foo/bar/xattr", mpoint);

rename(foo_bar_baz, foo_baz);

char buf2[113];
memset(buf2, 0, sizeof(buf2));
listxattr(xattr, buf2, sizeof(buf2));
removexattr(xattr, "user.mime_type");

}

int main(int argc, char *argv[]) {
activity(argv[1]);
return 0;
}

- Kernel message
Umount the image will leave the following message
[ 2910.995489] F2FS-fs (loop0): Mounted with checkpoint version = 2
[ 2918.416465] ==================================================================
[ 2918.416807] BUG: KASAN: slab-out-of-bounds in f2fs_iget+0xcb9/0x1a80
[ 2918.417009] Read of size 4 at addr ffff88018efc2068 by task a.out/1229

[ 2918.417311] CPU: 1 PID: 1229 Comm: a.out Not tainted 4.17.0+ #1
[ 2918.417314] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
[ 2918.417323] Call Trace:
[ 2918.417366] dump_stack+0x71/0xab
[ 2918.417401] print_address_description+0x6b/0x290
[ 2918.417407] kasan_report+0x28e/0x390
[ 2918.417411] ? f2fs_iget+0xcb9/0x1a80
[ 2918.417415] f2fs_iget+0xcb9/0x1a80
[ 2918.417422] ? f2fs_lookup+0x2e7/0x580
[ 2918.417425] f2fs_lookup+0x2e7/0x580
[ 2918.417433] ? __recover_dot_dentries+0x400/0x400
[ 2918.417447] ? legitimize_path.isra.29+0x5a/0xa0
[ 2918.417453] __lookup_slow+0x11c/0x220
[ 2918.417457] ? may_delete+0x2a0/0x2a0
[ 2918.417475] ? deref_stack_reg+0xe0/0xe0
[ 2918.417479] ? __lookup_hash+0xb0/0xb0
[ 2918.417483] lookup_slow+0x3e/0x60
[ 2918.417488] walk_component+0x3ac/0x990
[ 2918.417492] ? generic_permission+0x51/0x1e0
[ 2918.417495] ? inode_permission+0x51/0x1d0
[ 2918.417499] ? pick_link+0x3e0/0x3e0
[ 2918.417502] ? link_path_walk+0x4b1/0x770
[ 2918.417513] ? _raw_spin_lock_irqsave+0x25/0x50
[ 2918.417518] ? walk_component+0x990/0x990
[ 2918.417522] ? path_init+0x2e6/0x580
[ 2918.417526] path_lookupat+0x13f/0x430
[ 2918.417531] ? trailing_symlink+0x3a0/0x3a0
[ 2918.417534] ? do_renameat2+0x270/0x7b0
[ 2918.417538] ? __kasan_slab_free+0x14c/0x190
[ 2918.417541] ? do_renameat2+0x270/0x7b0
[ 2918.417553] ? kmem_cache_free+0x85/0x1e0
[ 2918.417558] ? do_renameat2+0x270/0x7b0
[ 2918.417563] filename_lookup+0x13c/0x280
[ 2918.417567] ? filename_parentat+0x2b0/0x2b0
[ 2918.417572] ? kasan_unpoison_shadow+0x31/0x40
[ 2918.417575] ? kasan_kmalloc+0xa6/0xd0
[ 2918.417593] ? strncpy_from_user+0xaa/0x1c0
[ 2918.417598] ? getname_flags+0x101/0x2b0
[ 2918.417614] ? path_listxattr+0x87/0x110
[ 2918.417619] path_listxattr+0x87/0x110
[ 2918.417623] ? listxattr+0xc0/0xc0
[ 2918.417637] ? mm_fault_error+0x1b0/0x1b0
[ 2918.417654] do_syscall_64+0x73/0x160
[ 2918.417660] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 2918.417676] RIP: 0033:0x7f2f3a3480d7
[ 2918.417677] Code: f0 ff ff 73 01 c3 48 8b 0d be dd 2b 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 b8 c2 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 91 dd 2b 00 f7 d8 64 89 01 48
[ 2918.417732] RSP: 002b:00007fff4095b7d8 EFLAGS: 00000206 ORIG_RAX: 00000000000000c2
[ 2918.417744] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f2f3a3480d7
[ 2918.417746] RDX: 0000000000000071 RSI: 00007fff4095b810 RDI: 000000000126a0c0
[ 2918.417749] RBP: 00007fff4095b890 R08: 000000000126a010 R09: 0000000000000000
[ 2918.417751] R10: 00000000000001ab R11: 0000000000000206 R12: 00000000004005e0
[ 2918.417753] R13: 00007fff4095b990 R14: 0000000000000000 R15: 0000000000000000

[ 2918.417853] Allocated by task 329:
[ 2918.418002] kasan_kmalloc+0xa6/0xd0
[ 2918.418007] kmem_cache_alloc+0xc8/0x1e0
[ 2918.418023] mempool_init_node+0x194/0x230
[ 2918.418027] mempool_init+0x12/0x20
[ 2918.418042] bioset_init+0x2bd/0x380
[ 2918.418052] blk_alloc_queue_node+0xe9/0x540
[ 2918.418075] dm_create+0x2c0/0x800
[ 2918.418080] dev_create+0xd2/0x530
[ 2918.418083] ctl_ioctl+0x2a3/0x5b0
[ 2918.418087] dm_ctl_ioctl+0xa/0x10
[ 2918.418092] do_vfs_ioctl+0x13e/0x8c0
[ 2918.418095] ksys_ioctl+0x66/0x70
[ 2918.418098] __x64_sys_ioctl+0x3d/0x50
[ 2918.418102] do_syscall_64+0x73/0x160
[ 2918.418106] entry_SYSCALL_64_after_hwframe+0x44/0xa9

[ 2918.418204] Freed by task 0:
[ 2918.418301] (stack is not available)

[ 2918.418521] The buggy address belongs to the object at ffff88018efc0000
which belongs to the cache biovec-max of size 8192
[ 2918.418894] The buggy address is located 104 bytes to the right of
8192-byte region [ffff88018efc0000, ffff88018efc2000)
[ 2918.419257] The buggy address belongs to the page:
[ 2918.419431] page:ffffea00063bf000 count:1 mapcount:0 mapping:ffff8801f2242540 index:0x0 compound_mapcount: 0
[ 2918.419702] flags: 0x17fff8000008100(slab|head)
[ 2918.419879] raw: 017fff8000008100 dead000000000100 dead000000000200 ffff8801f2242540
[ 2918.420101] raw: 0000000000000000 0000000000030003 00000001ffffffff 0000000000000000
[ 2918.420322] page dumped because: kasan: bad access detected

[ 2918.420599] Memory state around the buggy address:
[ 2918.420764] ffff88018efc1f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 2918.420975] ffff88018efc1f80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 2918.421194] >ffff88018efc2000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 2918.421406] ^
[ 2918.421627] ffff88018efc2080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 2918.421838] ffff88018efc2100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 2918.422046] ==================================================================
[ 2918.422264] Disabling lock debugging due to kernel taint
[ 2923.901641] BUG: unable to handle kernel paging request at ffff88018f0db000
[ 2923.901884] PGD 22226a067 P4D 22226a067 PUD 222273067 PMD 18e642063 PTE 800000018f0db061
[ 2923.902120] Oops: 0003 [#1] SMP KASAN PTI
[ 2923.902274] CPU: 1 PID: 1231 Comm: umount Tainted: G B 4.17.0+ #1
[ 2923.902490] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
[ 2923.902761] RIP: 0010:__memset+0x24/0x30
[ 2923.902906] Code: 90 90 90 90 90 90 66 66 90 66 90 49 89 f9 48 89 d1 83 e2 07 48 c1 e9 03 40 0f b6 f6 48 b8 01 01 01 01 01 01 01 01 48 0f af c6 <f3> 48 ab 89 d1 f3 aa 4c 89 c8 c3 90 49 89 f9 40 88 f0 48 89 d1 f3
[ 2923.903446] RSP: 0018:ffff88018ddf7ae0 EFLAGS: 00010206
[ 2923.903622] RAX: 0000000000000000 RBX: ffff8801d549d888 RCX: 1ffffffffffdaffb
[ 2923.903833] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88018f0daffc
[ 2923.904062] RBP: ffff88018efc206c R08: 1ffff10031df840d R09: ffff88018efc206c
[ 2923.904273] R10: ffffffffffffe1ee R11: ffffed0031df65fa R12: 0000000000000000
[ 2923.904485] R13: ffff8801d549dc98 R14: 00000000ffffc3db R15: ffffea00063bec80
[ 2923.904693] FS: 00007fa8b2f8a840(0000) GS:ffff8801f3b00000(0000) knlGS:0000000000000000
[ 2923.904937] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 2923.910080] CR2: ffff88018f0db000 CR3: 000000018f892000 CR4: 00000000000006e0
[ 2923.914930] Call Trace:
[ 2923.919724] f2fs_truncate_inline_inode+0x114/0x170
[ 2923.924487] f2fs_truncate_blocks+0x11b/0x7c0
[ 2923.929178] ? f2fs_truncate_data_blocks+0x10/0x10
[ 2923.933834] ? dqget+0x670/0x670
[ 2923.938437] ? f2fs_destroy_extent_tree+0xd6/0x270
[ 2923.943107] ? __radix_tree_lookup+0x2f/0x150
[ 2923.947772] f2fs_truncate+0xd4/0x1a0
[ 2923.952491] f2fs_evict_inode+0x5ab/0x610
[ 2923.957204] evict+0x15f/0x280
[ 2923.961898] __dentry_kill+0x161/0x250
[ 2923.966634] shrink_dentry_list+0xf3/0x250
[ 2923.971897] shrink_dcache_parent+0xa9/0x100
[ 2923.976561] ? shrink_dcache_sb+0x1f0/0x1f0
[ 2923.981177] ? wait_for_completion+0x8a/0x210
[ 2923.985781] ? migrate_swap_stop+0x2d0/0x2d0
[ 2923.990332] do_one_tree+0xe/0x40
[ 2923.994735] shrink_dcache_for_umount+0x3a/0xa0
[ 2923.999077] generic_shutdown_super+0x3e/0x1c0
[ 2924.003350] kill_block_super+0x4b/0x70
[ 2924.007619] deactivate_locked_super+0x65/0x90
[ 2924.011812] cleanup_mnt+0x5c/0xa0
[ 2924.015995] task_work_run+0xce/0xf0
[ 2924.020174] exit_to_usermode_loop+0x115/0x120
[ 2924.024293] do_syscall_64+0x12f/0x160
[ 2924.028479] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 2924.032709] RIP: 0033:0x7fa8b2868487
[ 2924.036888] Code: 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d e1 c9 2b 00 f7 d8 64 89 01 48
[ 2924.045750] RSP: 002b:00007ffc39824d58 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
[ 2924.050190] RAX: 0000000000000000 RBX: 00000000008ea030 RCX: 00007fa8b2868487
[ 2924.054604] RDX: 0000000000000001 RSI: 0000000000000000 RDI: 00000000008f4360
[ 2924.058940] RBP: 00000000008f4360 R08: 0000000000000000 R09: 0000000000000014
[ 2924.063186] R10: 00000000000006b2 R11: 0000000000000246 R12: 00007fa8b2d7183c
[ 2924.067418] R13: 0000000000000000 R14: 00000000008ea210 R15: 00007ffc39824fe0
[ 2924.071534] Modules linked in: snd_hda_codec_generic snd_hda_intel snd_hda_codec snd_hda_core snd_hwdep snd_pcm snd_timer joydev input_leds serio_raw snd soundcore mac_hid i2c_piix4 ib_iser rdma_cm iw_cm ib_cm ib_core configfs iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi btrfs zstd_decompress zstd_compress xxhash raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor raid6_pq libcrc32c raid1 raid0 multipath linear 8139too qxl ttm drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops drm crct10dif_pclmul crc32_pclmul ghash_clmulni_intel pcbc aesni_intel psmouse aes_x86_64 8139cp crypto_simd cryptd mii glue_helper pata_acpi floppy
[ 2924.098044] CR2: ffff88018f0db000
[ 2924.102520] ---[ end trace a8e0d899985faf31 ]---
[ 2924.107012] RIP: 0010:__memset+0x24/0x30
[ 2924.111448] Code: 90 90 90 90 90 90 66 66 90 66 90 49 89 f9 48 89 d1 83 e2 07 48 c1 e9 03 40 0f b6 f6 48 b8 01 01 01 01 01 01 01 01 48 0f af c6 <f3> 48 ab 89 d1 f3 aa 4c 89 c8 c3 90 49 89 f9 40 88 f0 48 89 d1 f3
[ 2924.120724] RSP: 0018:ffff88018ddf7ae0 EFLAGS: 00010206
[ 2924.125312] RAX: 0000000000000000 RBX: ffff8801d549d888 RCX: 1ffffffffffdaffb
[ 2924.129931] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88018f0daffc
[ 2924.134537] RBP: ffff88018efc206c R08: 1ffff10031df840d R09: ffff88018efc206c
[ 2924.139175] R10: ffffffffffffe1ee R11: ffffed0031df65fa R12: 0000000000000000
[ 2924.143825] R13: ffff8801d549dc98 R14: 00000000ffffc3db R15: ffffea00063bec80
[ 2924.148500] FS: 00007fa8b2f8a840(0000) GS:ffff8801f3b00000(0000) knlGS:0000000000000000
[ 2924.153247] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 2924.158003] CR2: ffff88018f0db000 CR3: 000000018f892000 CR4: 00000000000006e0
[ 2924.164641] BUG: Bad rss-counter state mm:00000000fa04621e idx:0 val:4
[ 2924.170007] BUG: Bad rss-counter
tate mm:00000000fa04621e idx:1 val:2

- Location
https://elixir.bootlin.com/linux/v4.18-rc3/source/fs/f2fs/inline.c#L78
memset(addr + from, 0, MAX_INLINE_DATA(inode) - from);
Here the length can be negative.

Reported-by Wen Xu <wen.xu@gatech.edu>
Signed-off-by: Chao Yu <yuchao0@huawei.com>
---
fs/f2fs/inode.c | 22 +++++++++++++++++-----
1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
index b0ab39d83235..6e661445ddd6 100644
--- a/fs/f2fs/inode.c
+++ b/fs/f2fs/inode.c
@@ -196,6 +196,7 @@ void f2fs_inode_chksum_set(struct f2fs_sb_info *sbi, struct page *page)
static bool sanity_check_inode(struct inode *inode, struct page *node_page)
{
struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
+ struct f2fs_inode_info *fi = F2FS_I(inode);
unsigned long long iblocks;

iblocks = le64_to_cpu(F2FS_INODE(node_page)->i_blocks);
@@ -237,6 +238,17 @@ static bool sanity_check_inode(struct inode *inode, struct page *node_page)
return false;
}

+ if (fi->i_extra_isize > F2FS_TOTAL_EXTRA_ATTR_SIZE ||
+ fi->i_extra_isize % sizeof(__le32)) {
+ set_sbi_flag(sbi, SBI_NEED_FSCK);
+ f2fs_msg(sbi->sb, KERN_WARNING,
+ "%s: inode (ino=%lx) has corrupted i_extra_isize: %d, "
+ "max: %lu",
+ __func__, inode->i_ino, fi->i_extra_isize,
+ F2FS_TOTAL_EXTRA_ATTR_SIZE);
+ return false;
+ }
+
if (F2FS_I(inode)->extent_tree) {
struct extent_info *ei = &F2FS_I(inode)->extent_tree->largest;

@@ -325,11 +337,6 @@ static int do_read_inode(struct inode *inode)

get_inline_info(inode, ri);

- if (!sanity_check_inode(inode, node_page)) {
- f2fs_put_page(node_page, 1);
- return -EINVAL;
- }
-
fi->i_extra_isize = f2fs_has_extra_attr(inode) ?
le16_to_cpu(ri->i_extra_isize) : 0;

@@ -349,6 +356,11 @@ static int do_read_inode(struct inode *inode)
fi->i_inline_xattr_size = 0;
}

+ if (!sanity_check_inode(inode, node_page)) {
+ f2fs_put_page(node_page, 1);
+ return -EINVAL;
+ }
+
/* check data exist */
if (f2fs_has_inline_data(inode) && !f2fs_exist_data(inode))
__recover_inline_status(inode, node_page);
--
2.16.2.17.g38e79b1fd
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