[syzbot] [block?] BUG: unable to handle kernel NULL pointer dereference in guard_bio_eod

[syzbot <syzbot+3291296495fc970e4b1c@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    6fea5fabd332 Merge tag 'mm-hotfixes-stable-2025-04-19-21-2..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15551ccc580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=b7c08f42e927242f
dashboard link: https://syzkaller.appspot.com/bug?extid=3291296495fc970e4b1c
compiler:       aarch64-linux-gnu-gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=17551ccc580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13a7f4cc580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/384ffdcca292/non_bootable_disk-6fea5fab.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/59473b9bbb43/vmlinux-6fea5fab.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a2e0095d3721/Image-6fea5fab.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3291296495fc970e4b1c@syzkaller.appspotmail.com

Unable to handle kernel NULL pointer dereference at virtual address 0000000000000008
Mem abort info:
  ESR = 0x0000000096000006
  EC = 0x25: DABT (current EL), IL = 32 bits
  SET = 0, FnV = 0
  EA = 0, S1PTW = 0
  FSC = 0x06: level 2 translation fault
Data abort info:
  ISV = 0, ISS = 0x00000006, ISS2 = 0x00000000
  CM = 0, WnR = 0, TnD = 0, TagAccess = 0
  GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
user pgtable: 4k pages, 52-bit VAs, pgdp=00000000442aa200
[0000000000000008] pgd=080000004b293403, p4d=080000004b27f403, pud=080000004b237403, pmd=0000000000000000
Internal error: Oops: 0000000096000006 [#1]  SMP
Modules linked in:
CPU: 1 UID: 0 PID: 6338 Comm: syz-executor150 Not tainted 6.15.0-rc2-syzkaller-00488-g6fea5fabd332 #0 PREEMPT 
Hardware name: linux,dummy-virt (DT)
pstate: 41402009 (nZcv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--)
pc : bdev_nr_sectors include/linux/blkdev.h:831 [inline]
pc : guard_bio_eod+0x18/0x210 block/bio.c:694
lr : mpage_bio_submit_read fs/mpage.c:74 [inline]
lr : do_mpage_readpage+0x2d0/0x6dc fs/mpage.c:296
sp : ffff80008331b820
x29: ffff80008331b820 x28: f4f0000004143e00 x27: ffff80008331b960
x26: 0000000000000001 x25: ffff80008331b940 x24: 0000000000000000
x23: 0000000000000000 x22: 0000000000000000 x21: ffffc1ffc02c9dc0
x20: 0000000000000010 x19: f4f0000004143e00 x18: 0000000000001000
x17: 0000000000000000 x16: 1e9e000000c6abc1 x15: 0000000000000000
x14: ffffc1ffc02c9dc0 x13: 0000000000000000 x12: f4f0000004143e00
x11: 0000000000000000 x10: ffffc1ffc02ca580 x9 : 0000000000000003
x8 : 00000000000000b8 x7 : fcf0000003f3b97c x6 : f6f0000006355c00
x5 : f6f0000006355c00 x4 : 0000000000000000 x3 : 0000000000000000
x2 : 0000000000000000 x1 : ffff8000803bbfc0 x0 : 0000000000000000
Call trace:
 bdev_nr_sectors include/linux/blkdev.h:831 [inline] (P)
 guard_bio_eod+0x18/0x210 block/bio.c:694 (P)
 mpage_bio_submit_read fs/mpage.c:74 [inline]
 do_mpage_readpage+0x2d0/0x6dc fs/mpage.c:296
 mpage_readahead+0xcc/0x164 fs/mpage.c:371
 blkdev_readahead+0x18/0x24 block/fops.c:472
 read_pages+0x70/0x2b8 mm/readahead.c:160
 page_cache_ra_unbounded+0x1d4/0x260 mm/readahead.c:280
 do_page_cache_ra mm/readahead.c:327 [inline]
 page_cache_ra_order+0x34c/0x400 mm/readahead.c:532
 do_sync_mmap_readahead mm/filemap.c:3262 [inline]
 filemap_fault+0x444/0x924 mm/filemap.c:3403
 __do_fault+0x3c/0x21c mm/memory.c:5098
 do_shared_fault mm/memory.c:5582 [inline]
 do_fault mm/memory.c:5656 [inline]
 do_pte_missing mm/memory.c:4160 [inline]
 handle_pte_fault mm/memory.c:5997 [inline]
 __handle_mm_fault+0xadc/0x1b00 mm/memory.c:6140
 handle_mm_fault+0x164/0x314 mm/memory.c:6309
 do_page_fault+0x118/0x688 arch/arm64/mm/fault.c:647
 do_translation_fault+0xac/0xbc arch/arm64/mm/fault.c:783
 do_mem_abort+0x44/0x94 arch/arm64/mm/fault.c:919
 el0_da+0x78/0xa8 arch/arm64/kernel/entry-common.c:604
 el0t_64_sync_handler+0xc4/0x138 arch/arm64/kernel/entry-common.c:765
 el0t_64_sync+0x1a4/0x1a8 arch/arm64/kernel/entry.S:600
Code: 910003fd a90153f3 aa0003f3 f9400400 (f9400400) 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	910003fd 	mov	x29, sp
   4:	a90153f3 	stp	x19, x20, [sp, #16]
   8:	aa0003f3 	mov	x19, x0
   c:	f9400400 	ldr	x0, [x0, #8]
* 10:	f9400400 	ldr	x0, [x0, #8] <-- trapping instruction


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