[syzbot] [net?] BUG: unable to handle kernel paging request in nsim_bpf

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 8de1e7afcc1c Merge branch 'for-next/core' into for-kernelci
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=158c647b680000
kernel config: https://syzkaller.appspot.com/x/.config?x=3e6feaeda5dcbc27
dashboard link: https://syzkaller.appspot.com/bug?extid=44c2416196b7c607f226
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=104da6eb680000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14df3787680000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/0f00907f9764/disk-8de1e7af.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0502fe78c60d/vmlinux-8de1e7af.xz
kernel image: https://storage.googleapis.com/syzbot-assets/192135168cc0/Image-8de1e7af.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+44c241...@syzkaller.appspotmail.com

netdevsim netdevsim0 netdevsim1: set [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim0 netdevsim2: set [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim0 netdevsim3: set [1, 0] type 2 family 0 port 6081 - 0
Unable to handle kernel paging request at virtual address dfff800000000003
KASAN: null-ptr-deref in range [0x0000000000000018-0x000000000000001f]
Mem abort info:
ESR = 0x0000000096000005
EC = 0x25: DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x05: level 1 translation fault
Data abort info:
ISV = 0, ISS = 0x00000005, ISS2 = 0x00000000
CM = 0, WnR = 0, TnD = 0, TagAccess = 0
GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
[dfff800000000003] address between user and kernel address ranges
Internal error: Oops: 0000000096000005 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 6085 Comm: syz-executor153 Not tainted 6.6.0-rc7-syzkaller-g8de1e7afcc1c #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : nsim_setup_prog_hw_checks drivers/net/netdevsim/bpf.c:320 [inline]
pc : nsim_bpf+0x1e0/0xae0 drivers/net/netdevsim/bpf.c:562
lr : nsim_bpf+0x8c/0xae0 drivers/net/netdevsim/bpf.c:554
sp : ffff800096c67790
x29: ffff800096c677a0 x28: dfff800000000000 x27: ffff700012d8cf00
x26: dfff800000000000 x25: ffff800096c67a00 x24: 0000000000000008
x23: ffff800096c67820 x22: 0000000000000018 x21: ffff800096c67820
x20: ffff0000d3834cc0 x19: ffff0000d3834000 x18: ffff800096c67580
x17: ffff8000805c1258 x16: ffff80008030c738 x15: 0000000000000000
x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000003
x11: ffff0000d4ab3780 x10: 00000000000000bc x9 : ffff800085ce8bf0
x8 : 0000000000000003 x7 : 0000000000000000 x6 : 0000000000000000
x5 : ffff800092dee000 x4 : 0000000000000000 x3 : ffff80008030c754
x2 : 0000000000000000 x1 : ffff80009001ef50 x0 : 0000000000000001
Call trace:
nsim_setup_prog_hw_checks drivers/net/netdevsim/bpf.c:320 [inline]
nsim_bpf+0x1e0/0xae0 drivers/net/netdevsim/bpf.c:562
dev_xdp_install+0x124/0x2f0 net/core/dev.c:9199
dev_xdp_attach+0xa4c/0xcc8 net/core/dev.c:9351
dev_xdp_attach_link net/core/dev.c:9370 [inline]
bpf_xdp_link_attach+0x300/0x710 net/core/dev.c:9540
link_create+0x2c0/0x68c kernel/bpf/syscall.c:4954
__sys_bpf+0x4d4/0x5dc kernel/bpf/syscall.c:5414
__do_sys_bpf kernel/bpf/syscall.c:5448 [inline]
__se_sys_bpf kernel/bpf/syscall.c:5446 [inline]
__arm64_sys_bpf+0x80/0x98 kernel/bpf/syscall.c:5446
__invoke_syscall arch/arm64/kernel/syscall.c:37 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:51
el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:136
do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:155
el0_svc+0x54/0x158 arch/arm64/kernel/entry-common.c:678
el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:696
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:595
Code: 96b3720d f94002c8 91006116 d343fec8 (387a6908)
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
0: 96b3720d bl 0xfffffffffacdc834
4: f94002c8 ldr x8, [x22]
8: 91006116 add x22, x8, #0x18
c: d343fec8 lsr x8, x22, #3
* 10: 387a6908 ldrb w8, [x8, x26] <-- trapping instruction


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
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If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
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If you want to undo deduplication, reply with:
#syz undup

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-...@vger.kernel.org, syzkall...@googlegroups.com.

***

Subject: [PATCH] Fix the null pointer deference in nsim_setup_prog_hw_checks
Author: kdipe...@gmail.com

#syz test: https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git 8de1e7afcc1c

Signed-off-by: Dipendra Khadka <kdipe...@gmail.com>
---
drivers/net/netdevsim/bpf.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/net/netdevsim/bpf.c b/drivers/net/netdevsim/bpf.c
index f60eb97e3a62..89206278b6cc 100644
--- a/drivers/net/netdevsim/bpf.c
+++ b/drivers/net/netdevsim/bpf.c
@@ -317,9 +317,11 @@ nsim_setup_prog_hw_checks(struct netdevsim *ns, struct netdev_bpf *bpf)
}

state = bpf->prog->aux->offload->dev_priv;
- if (WARN_ON(strcmp(state->state, "xlated"))) {
- NSIM_EA(bpf->extack, "offloading program in bad state");
- return -EINVAL;
+ if(state) {
+ if (WARN_ON(strcmp(state->state, "xlated"))) {
+ NSIM_EA(bpf->extack, "offloading program in bad state");
+ return -EINVAL;
+ }
}
return 0;
}
--
2.34.1

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
BUG: unable to handle kernel paging request in nsim_xdp_set_prog

Unable to handle kernel paging request at virtual address dfff800000000004
KASAN: null-ptr-deref in range [0x0000000000000020-0x0000000000000027]

Mem abort info:
ESR = 0x0000000096000005
EC = 0x25: DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x05: level 1 translation fault
Data abort info:
ISV = 0, ISS = 0x00000005, ISS2 = 0x00000000
CM = 0, WnR = 0, TnD = 0, TagAccess = 0
GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0

[dfff800000000004] address between user and kernel address ranges

Internal error: Oops: 0000000096000005 [#1] PREEMPT SMP
Modules linked in:

CPU: 0 PID: 6540 Comm: syz-executor.0 Not tainted 6.6.0-rc7-syzkaller-00089-g8de1e7afcc1c-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023

pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)

pc : nsim_prog_set_loaded drivers/net/netdevsim/bpf.c:100 [inline]
pc : nsim_bpf_offload drivers/net/netdevsim/bpf.c:113 [inline]
pc : nsim_xdp_offload_prog drivers/net/netdevsim/bpf.c:189 [inline]
pc : nsim_xdp_set_prog+0x3f4/0x568 drivers/net/netdevsim/bpf.c:208
lr : nsim_prog_set_loaded drivers/net/netdevsim/bpf.c:99 [inline]
lr : nsim_bpf_offload drivers/net/netdevsim/bpf.c:113 [inline]
lr : nsim_xdp_offload_prog drivers/net/netdevsim/bpf.c:189 [inline]
lr : nsim_xdp_set_prog+0x3d0/0x568 drivers/net/netdevsim/bpf.c:208
sp : ffff800097047730
x29: ffff800097047730 x28: dfff800000000000 x27: 1fffe000196b819f
x26: ffff800094eee000 x25: 1ffff000129ddc07 x24: dfff800000000000
x23: 0000000000000001 x22: ffff800094eee038 x21: 0000000000000020
x20: ffff0000cb5c0d18 x19: ffff800097047820 x18: ffff800097047580

x17: ffff8000805c1258 x16: ffff80008030c738 x15: 0000000000000000

x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000001
x11: 0000000000000000 x10: 0000000000000000 x9 : 0000000000000000
x8 : 0000000000000004 x7 : 0000000000000000 x6 : 0000000000000000
x5 : ffff800094eee000 x4 : 0000000000000000 x3 : ffff80008030c754
x2 : ffff0000cb5c0d18 x1 : 0000000000000001 x0 : 0000000000000000
Call trace:
nsim_prog_set_loaded drivers/net/netdevsim/bpf.c:100 [inline]
nsim_bpf_offload drivers/net/netdevsim/bpf.c:113 [inline]
nsim_xdp_offload_prog drivers/net/netdevsim/bpf.c:189 [inline]
nsim_xdp_set_prog+0x3f4/0x568 drivers/net/netdevsim/bpf.c:208
nsim_bpf+0x5ac/0xaec

dev_xdp_install+0x124/0x2f0 net/core/dev.c:9199
dev_xdp_attach+0xa4c/0xcc8 net/core/dev.c:9351
dev_xdp_attach_link net/core/dev.c:9370 [inline]
bpf_xdp_link_attach+0x300/0x710 net/core/dev.c:9540
link_create+0x2c0/0x68c kernel/bpf/syscall.c:4954
__sys_bpf+0x4d4/0x5dc kernel/bpf/syscall.c:5414
__do_sys_bpf kernel/bpf/syscall.c:5448 [inline]
__se_sys_bpf kernel/bpf/syscall.c:5446 [inline]
__arm64_sys_bpf+0x80/0x98 kernel/bpf/syscall.c:5446
__invoke_syscall arch/arm64/kernel/syscall.c:37 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:51
el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:136
do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:155
el0_svc+0x54/0x158 arch/arm64/kernel/entry-common.c:678
el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:696
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:595

Code: 96b36ecd f94002a8 91008115 d343fea8 (38f86908)

---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):

0: 96b36ecd bl 0xfffffffffacdbb34
4: f94002a8 ldr x8, [x21]
8: 91008115 add x21, x8, #0x20
c: d343fea8 lsr x8, x21, #3
* 10: 38f86908 ldrsb w8, [x8, x24] <-- trapping instruction


Tested on:

commit: 8de1e7af Merge branch 'for-next/core' into for-kernelci
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=1097a35b680000

kernel config: https://syzkaller.appspot.com/x/.config?x=3e6feaeda5dcbc27
dashboard link: https://syzkaller.appspot.com/bug?extid=44c2416196b7c607f226
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64

patch: https://syzkaller.appspot.com/x/patch.diff?x=120c37df680000

[Stanislav Fomichev]

On 11/08, syzbot wrote:
> Hello,
>
> syzbot found the following issue on:

Looks like we need to have a distinction between dev-bound vs
dev-offloaded. I'll try to poke it.

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-...@vger.kernel.org, syzkall...@googlegroups.com.

***

Subject: [PATCH] net: Fix the null pointer deference in nsim_setup_prog_hw_checks

Author: kdipe...@gmail.com

#syz test: https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git 8de1e7afcc1c

Signed-off-by: Dipendra Khadka <kdipe...@gmail.com>
---

drivers/net/netdevsim/bpf.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/net/netdevsim/bpf.c b/drivers/net/netdevsim/bpf.c
index f60eb97e3a62..e407efb0e3de 100644
--- a/drivers/net/netdevsim/bpf.c
+++ b/drivers/net/netdevsim/bpf.c
@@ -97,7 +97,8 @@ static void nsim_prog_set_loaded(struct bpf_prog *prog, bool loaded)
return;

state = prog->aux->offload->dev_priv;
- state->is_loaded = loaded;
+ if (state)
+ state->is_loaded = loaded;
}

static int
@@ -317,10 +318,12 @@ nsim_setup_prog_hw_checks(struct netdevsim *ns, struct netdev_bpf *bpf)

}

state = bpf->prog->aux->offload->dev_priv;
- if (WARN_ON(strcmp(state->state, "xlated"))) {
- NSIM_EA(bpf->extack, "offloading program in bad state");
- return -EINVAL;

- }
+ if (state) {

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+44c241...@syzkaller.appspotmail.com

Tested on:

commit: 8de1e7af Merge branch 'for-next/core' into for-kernelci
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git

console output: https://syzkaller.appspot.com/x/log.txt?x=13a0c3c0e80000

kernel config: https://syzkaller.appspot.com/x/.config?x=3e6feaeda5dcbc27
dashboard link: https://syzkaller.appspot.com/bug?extid=44c2416196b7c607f226
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64

patch: https://syzkaller.appspot.com/x/patch.diff?x=15592737680000

Note: testing is done by a robot and is best-effort only.