Re: [f2fs-dev] [syzbot] [f2fs?] KASAN: slab-use-after-free Read in f2fs_filemap_fault

From: Chao Yu
Date: Wed Mar 13 2024 - 22:19:31 EST


On 2024/3/13 9:31, Jaegeuk Kim wrote:
On 03/12, Ed Tsai (蔡宗軒) wrote:
On Mon, 2024-01-15 at 20:05 +0800, Hillf Danton wrote:

...

--- x/fs/f2fs/file.c
+++ y/fs/f2fs/file.c
@@ -39,6 +39,7 @@
static vm_fault_t f2fs_filemap_fault(struct vm_fault *vmf)
{
struct inode *inode = file_inode(vmf->vma->vm_file);
+ vm_flags_t flags = vmf->vma->vm_flags;
vm_fault_t ret;
ret = filemap_fault(vmf);
@@ -46,7 +47,7 @@ static vm_fault_t f2fs_filemap_fault(str
f2fs_update_iostat(F2FS_I_SB(inode), inode,
APP_MAPPED_READ_IO,
F2FS_BLKSIZE);
- trace_f2fs_filemap_fault(inode, vmf->pgoff, vmf->vma-
vm_flags, ret);
+ trace_f2fs_filemap_fault(inode, vmf->pgoff, flags, ret);
return ret;
}
--

Hi Jaegeuk,

We recently encountered this slabe-use-after-free issue in KASAN as
well. Could you please review the patch above and merge it into f2fs?

Where is the patch?

Hi, all,

I'd like to fix this issue in 6.9-rc1, so I submitted a formal patch based on
above code, and the patch has been tested by syzbot.

https://lore.kernel.org/linux-f2fs-devel/20240314020528.3051533-1-chao@xxxxxxxxxx

Hillf, may I change author of the patch to you? :)

Thanks,



Best,
Ed

==================================================================
[29195.369964][T31720] BUG: KASAN: slab-use-after-free in
f2fs_filemap_fault+0x50/0xe0
[29195.370971][T31720] Read at addr f7ffff80454ebde0 by task AsyncTask
#11/31720
[29195.371881][T31720] Pointer tag: [f7], memory tag: [f1]
[29195.372549][T31720]
[29195.372838][T31720] CPU: 2 PID: 31720 Comm: AsyncTask #11 Tainted:
G W OE 6.6.17-android15-0-gcb5ba718a525 #1
[29195.374862][T31720] Call trace:
[29195.375268][T31720] dump_backtrace+0xec/0x138
[29195.375848][T31720] show_stack+0x18/0x24
[29195.376365][T31720] dump_stack_lvl+0x50/0x6c
[29195.376943][T31720] print_report+0x1b0/0x714
[29195.377520][T31720] kasan_report+0xc4/0x124
[29195.378076][T31720] __do_kernel_fault+0xb8/0x26c
[29195.378694][T31720] do_bad_area+0x30/0xdc
[29195.379226][T31720] do_tag_check_fault+0x20/0x34
[29195.379834][T31720] do_mem_abort+0x58/0x104
[29195.380388][T31720] el1_abort+0x3c/0x5c
[29195.380899][T31720] el1h_64_sync_handler+0x54/0x90
[29195.381529][T31720] el1h_64_sync+0x68/0x6c
[29195.382069][T31720] f2fs_filemap_fault+0x50/0xe0
[29195.382678][T31720] __do_fault+0xc8/0xfc
[29195.383209][T31720] handle_mm_fault+0xb44/0x10c4
[29195.383816][T31720] do_page_fault+0x294/0x48c
[29195.384395][T31720] do_translation_fault+0x38/0x54
[29195.385023][T31720] do_mem_abort+0x58/0x104
[29195.385577][T31720] el0_da+0x44/0x78
[29195.386057][T31720] el0t_64_sync_handler+0x98/0xbc
[29195.386688][T31720] el0t_64_sync+0x1a8/0x1ac
[29195.387249][T31720]
[29195.387534][T31720] Allocated by task 14784:
[29195.388085][T31720] kasan_save_stack+0x40/0x70
[29195.388672][T31720] save_stack_info+0x34/0x128
[29195.389259][T31720] kasan_save_alloc_info+0x14/0x20
[29195.389901][T31720] __kasan_slab_alloc+0x168/0x174
[29195.390530][T31720] slab_post_alloc_hook+0x88/0x3a4
[29195.391168][T31720] kmem_cache_alloc+0x18c/0x2c8
[29195.391771][T31720] vm_area_alloc+0x2c/0xe8
[29195.392327][T31720] mmap_region+0x440/0xa94
[29195.392888][T31720] do_mmap+0x3d0/0x524
[29195.393399][T31720] vm_mmap_pgoff+0x1a0/0x1f8
[29195.393980][T31720] ksys_mmap_pgoff+0x78/0xf4
[29195.394557][T31720] __arm64_sys_mmap+0x34/0x44
[29195.395138][T31720] invoke_syscall+0x58/0x114
[29195.395727][T31720] el0_svc_common+0x80/0xe0
[29195.396292][T31720] do_el0_svc+0x1c/0x28
[29195.396812][T31720] el0_svc+0x38/0x68
[29195.397302][T31720] el0t_64_sync_handler+0x68/0xbc
[29195.397932][T31720] el0t_64_sync+0x1a8/0x1ac
[29195.398492][T31720]
[29195.398778][T31720] Freed by task 0:
[29195.399240][T31720] kasan_save_stack+0x40/0x70
[29195.399825][T31720] save_stack_info+0x34/0x128
[29195.400412][T31720] kasan_save_free_info+0x18/0x28
[29195.401043][T31720] ____kasan_slab_free+0x254/0x25c
[29195.401682][T31720] __kasan_slab_free+0x10/0x20
[29195.402278][T31720] slab_free_freelist_hook+0x174/0x1e0
[29195.402961][T31720] kmem_cache_free+0xc4/0x348
[29195.403544][T31720] __vm_area_free+0x84/0xa4
[29195.404103][T31720] vm_area_free_rcu_cb+0x10/0x20
[29195.404719][T31720] rcu_do_batch+0x214/0x720
[29195.405284][T31720] rcu_core+0x1b0/0x408
[29195.405800][T31720] rcu_core_si+0x10/0x20
[29195.406348][T31720] __do_softirq+0x120/0x3f4
[29195.406907][T31720]
[29195.407191][T31720] The buggy address belongs to the object at
ffffff80454ebdc0
[29195.407191][T31720] which belongs to the cache vm_area_struct of
size 176
[29195.408978][T31720] The buggy address is located 32 bytes inside of
[29195.408978][T31720] 176-byte region [ffffff80454ebdc0,
ffffff80454ebe70)
[29195.410625][T31720]
[29195.410911][T31720] The buggy address belongs to the physical page:
[29195.411709][T31720] page:0000000058f0f2f1 refcount:1 mapcount:0
mapping:0000000000000000 index:0x0 pfn:0xc54eb
[29195.412980][T31720] anon flags:
0x4000000000000800(slab|zone=1|kasantag=0x0)
[29195.413880][T31720] page_type: 0xffffffff()
[29195.414418][T31720] raw: 4000000000000800 f6ffff8002904500
fffffffe076fc8c0 dead000000000007
[29195.415488][T31720] raw: 0000000000000000 0000000000170017
00000001ffffffff 0000000000000000


_______________________________________________
Linux-f2fs-devel mailing list
Linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx
https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel