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Dear Linux Kernel Developers,<br>
I have reason to believe that the commit
4012603cbd469223f225637d265a233f034c567a,<br>
which was backported to the linux-5.10 branch, is introducing a bug
that leads to a kernel crash.<br>
<br>
<b>Environment Details:</b><br>
<ol>
<li>Kernel Version: linux-5.10.234</li>
<li>Architecture: aarch64</li>
<li>Kernel Configuration: Available at <a
class="moz-txt-link-freetext"
href="https://syzkaller.appspot.com/bug?extid=75dc11b3aa0369757b7c">https://syzkaller.appspot.com/bug?extid=75dc11b3aa0369757b7c</a></li>
<li>QEMU Version: 8.2.2</li>
</ol>
<b>QEMU Launch Command:</b><br>
<br>
qemu-system-aarch64 \<br>
-m 4G \<br>
-smp 4,sockets=1,cores=4,threads=1 \<br>
-cpu cortex-a57 \<br>
-machine virt,accel=tcg \<br>
-kernel /home/user/lvc/linux-stable/arch/arm64/boot/Image \<br>
-append "console=ttyS0 root=/dev/vda2 earlyprintk=serial
net.ifnames=0 rw debug loglevel=8" \<br>
-drive
file=/home/user/lvc/image/disk.raw,format=raw,if=virtio,index=1 \<br>
-bios /usr/share/AAVMF/AAVMF_CODE.fd \<br>
-netdev user,id=net0,hostfwd=tcp::10022-:22 \<br>
-device virtio-net-device,netdev=net0 \<br>
-nographic<br>
<p><b>Steps to Reproduce:</b></p>
<ol>
<li>mount -t sysfs sysfs /sys</li>
<li>mount -t proc proc /proc</li>
<li>mount -t efivarfs efivarfs /sys/firmware/efi/efivars</li>
<li>tools/testing/selftests/efivarfs/efivarfs.sh</li>
</ol>
<p><b>Crash log:</b></p>
[ 101.403235][ T38] Unable to handle kernel paging request at
virtual address ffffa00023b20000<br>
[ 101.403905][ T38] Mem abort info:<br>
[ 101.404159][ T38] ESR = 0x96000047<br>
[ 101.404448][ T38] EC = 0x25: DABT (current EL), IL = 32 bits<br>
[ 101.404748][ T38] SET = 0, FnV = 0<br>
[ 101.404988][ T38] EA = 0, S1PTW = 0<br>
[ 101.405233][ T38] Data abort info:<br>
[ 101.405469][ T38] ISV = 0, ISS = 0x00000047<br>
[ 101.405721][ T38] CM = 0, WnR = 1<br>
[ 101.406070][ T38] swapper pgtable: 4k pages, 48-bit VAs,
pgdp=0000000103336000<br>
[ 101.406415][ T38] [ffffa00023b20000] pgd=000000013ffff003,
p4d=000000013ffff003, pud=000000013fffe003, pmd=000000013fff9003,
pte=0000000000000000<br>
[ 101.407997][ T38] Internal error: Oops: 0000000096000047 [#1]
PREEMPT SMP<br>
[ 101.408446][ T38] Modules linked in:<br>
[ 101.409010][ T38] CPU: 1 PID: 38 Comm: kworker/u8:2 Not tainted
5.10.234 #61<br>
[ 101.409376][ T38] Hardware name: QEMU QEMU Virtual Machine,
BIOS 2024.02-2ubuntu0.1 10/25/2024<br>
[ 101.410689][ T38] Workqueue: efi_rts_wq efi_call_rts<br>
[ 101.411219][ T38] pstate: 000003c5 (nzcv DAIF -PAN -UAO -TCO
BTYPE=--)<br>
[ 101.411574][ T38] pc : el1_sync+0xc/0x140<br>
[ 101.411930][ T38] lr : 0x0<br>
[ 101.412132][ T38] sp : ffffa00023b1ffd0<br>
[ 101.412363][ T38] x29: 0000000000000000 x28: ffff0000cc741a80 <br>
[ 101.412761][ T38] x27: 0000000000000001 x26: 0000000000e800e8 <br>
[ 101.413117][ T38] x25: 0000000000800080 x24: ffff940004765298 <br>
[ 101.413465][ T38] x23: 00000000100003c5 x22: ffffa00018c95600 <br>
[ 101.413809][ T38] x21: ffffa0001923a980 x20: ffffa00018d30380 <br>
[ 101.414170][ T38] x19: ffffa0001bab8008 x18: 1fffe000198e8491 <br>
[ 101.414515][ T38] x17: 0000000000000000 x16: ffffa000102a26c0 <br>
[ 101.414882][ T38] x15: 0000000000000001 x14: ffff0000ccf34400 <br>
[ 101.415277][ T38] x13: 000000000000003c x12: ffff0000ccf34000 <br>
[ 101.415656][ T38] x11: 0000000000000018 x10: 0000000000000054 <br>
[ 101.416072][ T38] x9 : 4fc79849210be57c x8 : 11d293ca8be4df61 <br>
[ 101.416446][ T38] x7 : 0000000041b58ab3 x6 : ffff94000476522a <br>
[ 101.416820][ T38] x5 : 0000002200000000 x4 : 0000000200000000 <br>
[ 101.417190][ T38] x3 : 1fffe000198e8352 x2 : ffffa0001923a820 <br>
[ 101.417560][ T38] x1 : ffff0000cc741a80 x0 : 0000000000000000 <br>
[ 101.418109][ T38] Call trace:<br>
[ 101.418601][ T38] Code: d503201f a90007e0 a9010fe2 a90217e4
(a9031fe6) <br>
[ 101.419579][ T38] ---[ end trace 61316cddfdbbcb95 ]---<br>
[ 103.623221][ T38] Kernel panic - not syncing: Oops: Fatal
exception<br>
[ 103.623723][ T38] SMP: stopping secondary CPUs<br>
[ 105.221708][ T38] SMP: failed to stop secondary CPUs 0-3<br>
[ 105.222306][ T38] Kernel Offset: disabled<br>
[ 105.222711][ T38] CPU features: 0x28240022,61002082<br>
[ 105.222969][ T38] Memory Limit: none<br>
<br>
I identified this commit as the potential cause of the crash using
git bisect.<br>
The issue is reproducible with the above setup and configuration. If
you need<br>
more details or logs, I am more than willing to provide them. Thank
you for <br>
your attention to this matter.<br>
<br>
Best regards,<br>
<br>
Alexey Nepomnyashih<br>
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