syzbot
Unable to handle kernel read from unreadable memory at virtual address ADDR
Status:
upstream: reported C repro on 2026/09/24 23:31
Reported-by: syzbot+191b8352be136af263b1@syzkaller.appspotmail.com
First crash: 4d02h, last: 4d01h
Sample crash report:
Unable to handle kernel read from unreadable memory at virtual address ffff8000211fb000
KASAN: probably user-memory-access in range [0x0000000108fd8000-0x0000000108fd8007]
Mem abort info:
ESR = 0x000000009600000f
EC = 0x25: DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x0f: level 3 permission fault
Data abort info:
ISV = 0, ISS = 0x0000000f
CM = 0, WnR = 0
swapper pgtable: 4k pages, 48-bit VAs, pgdp=000000020dd64000
[ffff8000211fb000] pgd=100000023ffff003, p4d=100000023ffff003, pud=100000023fffe003, pmd=100000010a56e003, pte=0160010000000fd3
Internal error: Oops: 000000009600000f [#1] PREEMPT SMP
Modules linked in:
CPU: 1 PID: 4467 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/14/2026
pstate: 22400005 (nzCv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : __raw_readq arch/arm64/include/asm/io.h:86 [inline]
pc : __memcpy_fromio+0x2c8/0x454 arch/arm64/kernel/io.c:25
lr : __memcpy_fromio+0x2b0/0x454 arch/arm64/kernel/io.c:24
sp : ffff8000216376f0
x29: ffff8000216376f0 x28: dfff800000000000 x27: 0160010000000fd3
x26: 0160010000000fd3 x25: ffff8000211fb000 x24: 0000000000001000
x23: dfff800000000000 x22: ffff0000daa5cd60 x21: 0000000000000298
x20: ffff8000211fb000 x19: ffff0000daa5cd68 x18: 0000000000000000
x17: 0000000000000000 x16: ffff8000082f287c x15: 000000000004ffff
x14: ffff7000042c6ec4 x13: 1ffff000042c6ec4 x12: 0000000000000004
x11: ff00800008047604 x10: 0000000000000000 x9 : ffff0000d445b800
x8 : 1fffe0001b54b9ac x7 : ffff8000087ef3a0 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000001 x3 : ffff8000082f29a4
x2 : 00000000000002a0 x1 : 00000000000002a0 x0 : 0000000000000007
Call trace:
__memcpy_fromio+0x2c8/0x454 arch/arm64/kernel/io.c:25
generic_access_phys+0x2a4/0x2bc mm/memory.c:5684
kernfs_vma_access+0x14c/0x1d4 fs/kernfs/file.c:444
__access_remote_vm+0x2a4/0x5a8 mm/memory.c:5736
access_remote_vm+0x48/0x60 mm/memory.c:5784
environ_read+0x218/0x484 fs/proc/base.c:1020
do_loop_readv_writev fs/read_write.c:-1 [inline]
do_iter_read+0x39c/0x8b4 fs/read_write.c:798
vfs_readv fs/read_write.c:916 [inline]
do_preadv+0x1e0/0x32c fs/read_write.c:1008
__do_sys_preadv fs/read_write.c:1058 [inline]
__se_sys_preadv fs/read_write.c:1053 [inline]
__arm64_sys_preadv+0xa4/0xbc fs/read_write.c:1053
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140
do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204
el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585
Code: aa1303f6 91002273 aa0803f5 d343fec8 (f9400298)
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
0: aa1303f6 mov x22, x19
4: 91002273 add x19, x19, #0x8
8: aa0803f5 mov x21, x8
c: d343fec8 lsr x8, x22, #3
* 10: f9400298 ldr x24, [x20] <-- trapping instruction
* Struck through repros no longer work on HEAD.