[syzbot] [kernel?] WARNING in its_msi_teardown

[syzbot] [kernel?] WARNING in its_msi_teardown

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    b66b0005b6ce Merge branches 'for-next/fixes' and 'for-next..
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=15f7d746580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=72c97575381cec47
dashboard link: https://syzkaller.appspot.com/bug?extid=229d761b8a110e6de517
compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
userspace arch: arm64
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1667e09e580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=17525fde580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/63e3226301fe/disk-b66b0005.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b268844cbd22/vmlinux-b66b0005.xz
kernel image: https://storage.googleapis.com/syzbot-assets/9440dfc93d1e/Image-b66b0005.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+229d761b8a110e6de517@syzkaller.appspotmail.com

 el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121
 do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140
 el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:736
 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594
------------[ cut here ]------------
WARNING: drivers/irqchip/irq-gic-v3-its.c:2251 at its_lpi_free drivers/irqchip/irq-gic-v3-its.c:2251 [inline], CPU#0: syz.0.18/4916
WARNING: drivers/irqchip/irq-gic-v3-its.c:2251 at its_msi_teardown+0x3a4/0x424 drivers/irqchip/irq-gic-v3-its.c:3644, CPU#0: syz.0.18/4916
Modules linked in:
CPU: 0 UID: 0 PID: 4916 Comm: syz.0.18 Not tainted syzkaller #0 PREEMPT 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/02/2026
pstate: 83400005 (Nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
pc : its_lpi_free drivers/irqchip/irq-gic-v3-its.c:2251 [inline]
pc : its_msi_teardown+0x3a4/0x424 drivers/irqchip/irq-gic-v3-its.c:3644
lr : its_lpi_free drivers/irqchip/irq-gic-v3-its.c:2251 [inline]
lr : its_msi_teardown+0x3a4/0x424 drivers/irqchip/irq-gic-v3-its.c:3644
sp : ffff800098017560
x29: ffff8000980175f0 x28: ffff0000cfc75930 x27: 1fffe00019f8eb26
x26: 1fffe00019f8eb22 x25: ffff0000c13e1000 x24: dfff800000000000
x23: ffff700013002eac x22: 00000000fffffff4 x21: ffff800098017580
x20: ffff0000c1e07ce0 x19: ffff0000cfc75900 x18: 00000000ffffffff
x17: 70202c31206c6176 x16: 0000000000000001 x15: 0000000000000000
x14: 0000000000000000 x13: 0000000000000001 x12: 0000000000000000
x11: 0000000000000000 x10: 0000000000000003 x9 : 0000000000000000
x8 : 0000000000000000 x7 : 0000000000000000 x6 : 0000000000000000
x5 : 00000000ffffffff x4 : 0000000000000cc0 x3 : ffff800081ba1c7c
x2 : 00000000fffffff4 x1 : ffff0000cfb10000 x0 : 0000000000000000
Call trace:
 its_lpi_free drivers/irqchip/irq-gic-v3-its.c:2251 [inline] (P)
 its_msi_teardown+0x3a4/0x424 drivers/irqchip/irq-gic-v3-its.c:3644 (P)
 its_msi_teardown+0xa0/0xb8 drivers/irqchip/irq-gic-its-msi-parent.c:249
 msi_remove_device_irq_domain+0x16c/0x27c kernel/irq/msi.c:1127
 msi_device_data_release+0x38/0x9c kernel/irq/msi.c:293
 dr_node_release+0x4c/0x5c drivers/base/devres.c:122
 release_nodes+0xac/0x108 drivers/base/devres.c:546
 devres_release_all+0x138/0x1a4 drivers/base/devres.c:576
 device_unbind_cleanup+0x80/0x1c8 drivers/base/dd.c:597
 __device_release_driver drivers/base/dd.c:1354 [inline]
 device_release_driver_internal+0x19c/0x20c drivers/base/dd.c:1372
 device_release_driver+0x28/0x38 drivers/base/dd.c:1395
 pci_stop_dev drivers/pci/remove.c:27 [inline]
 pci_stop_bus_device+0x108/0x14c drivers/pci/remove.c:93
 pci_stop_and_remove_bus_device+0x84/0xd0 drivers/pci/remove.c:128
 pci_stop_and_remove_bus_device_locked+0x24/0x38 drivers/pci/remove.c:136
 remove_store+0xdc/0x148 drivers/pci/pci-sysfs.c:523
 dev_attr_store+0x6c/0x90 drivers/base/core.c:2505
 sysfs_kf_write+0xe0/0x108 fs/sysfs/file.c:145
 kernfs_fop_write_iter+0x260/0x3b8 fs/kernfs/file.c:345
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x51c/0xa0c fs/read_write.c:687
 ksys_write+0x12c/0x228 fs/read_write.c:739
 __do_sys_write fs/read_write.c:750 [inline]
 __se_sys_write fs/read_write.c:747 [inline]
 __arm64_sys_write+0x7c/0x90 fs/read_write.c:747
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121
 do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140
 el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:736
 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594
irq event stamp: 1608
hardirqs last  enabled at (1607): [<ffff8000868e3f4c>] irqentry_exit_to_kernel_mode_after_preempt include/linux/irq-entry-common.h:507 [inline]
hardirqs last  enabled at (1607): [<ffff8000868e3f4c>] arm64_exit_to_kernel_mode+0x80/0x94 arch/arm64/kernel/entry-common.c:62
hardirqs last disabled at (1608): [<ffff8000868dfe78>] el1_brk64+0x20/0x54 arch/arm64/kernel/entry-common.c:425
softirqs last  enabled at (1528): [<ffff800084c10fac>] __alloc_skb+0x1c0/0x610 net/core/skbuff.c:698
softirqs last disabled at (1526): [<ffff800084c10f94>] local_bh_disable include/linux/bottom_half.h:20 [inline]
softirqs last disabled at (1526): [<ffff800084c10f94>] __alloc_skb+0x1a8/0x610 net/core/skbuff.c:697
---[ end trace 0000000000000000 ]---
pci 0000:00:01.0: [1af4:1005] type 00 class 0x00ff00 conventional PCI endpoint
pci 0000:00:01.0: BAR 0 [io  0x1000-0x101f]
pci 0000:00:01.0: BAR 1 [mem 0x10110080-0x101100bf]
pci 0000:00:01.0: BAR 1 [mem 0x10110080-0x101100bf]: assigned
pci 0000:00:01.0: BAR 0 [io  0x1000-0x101f]: assigned
virtio-pci 0000:00:01.0: virtio_pci: leaving for legacy driver


---
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Forwarded: Re: [syzbot] [kernel?] WARNING in its_msi_teardown

[syzbot]

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

***

Subject: Re: [syzbot] [kernel?] WARNING in its_msi_teardown
Author: rihyeon8648@gmail.com

#syz test

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index 6f5811aae59c..f324d3df56c0 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -2108,11 +2108,15 @@ static struct lpi_range *mk_lpi_range(u32 base, u32 span)
 {
 	struct lpi_range *range;
 
-	range = kmalloc_obj(*range);
-	if (range) {
-		range->base_id = base;
-		range->span = span;
-	}
+	/*
+	 * Handing a range back is not allowed to fail: the callers of
+	 * free_lpi_range() have no way of reporting an error, and losing the
+	 * range here would leak the LPIs for good. This is a small, order-0
+	 * request and lpi_range_lock is a mutex, so the context is sleepable.
+	 */
+	range = kmalloc_obj(*range, GFP_KERNEL | __GFP_NOFAIL);
+	range->base_id = base;
+	range->span = span;
 
 	return range;
 }
@@ -2158,13 +2162,11 @@ static void merge_lpi_ranges(struct lpi_range *a, struct lpi_range *b)
 	kfree(a);
 }
 
-static int free_lpi_range(u32 base, u32 nr_lpis)
+static void free_lpi_range(u32 base, u32 nr_lpis)
 {
 	struct lpi_range *new, *old;
 
 	new = mk_lpi_range(base, nr_lpis);
-	if (!new)
-		return -ENOMEM;
 
 	mutex_lock(&lpi_range_lock);
 
@@ -2188,14 +2190,12 @@ static int free_lpi_range(u32 base, u32 nr_lpis)
 	merge_lpi_ranges(new, list_next_entry(new, entry));
 
 	mutex_unlock(&lpi_range_lock);
-	return 0;
 }
 
-static int __init its_lpi_init(u32 id_bits)
+static void __init its_lpi_init(u32 id_bits)
 {
 	u32 lpis = (1UL << id_bits) - 8192;
 	u32 numlpis;
-	int err;
 
 	numlpis = 1UL << GICD_TYPER_NUM_LPIS(gic_rdists->gicd_typer);
 
@@ -2209,9 +2209,8 @@ static int __init its_lpi_init(u32 id_bits)
 	 * Initializing the allocator is just the same as freeing the
 	 * full range of LPIs.
 	 */
-	err = free_lpi_range(8192, lpis);
+	free_lpi_range(8192, lpis);
 	pr_debug("ITS: Allocator initialized for %u LPIs\n", lpis);
-	return err;
 }
 
 static unsigned long *its_lpi_alloc(int nr_irqs, u32 *base, int *nr_ids)
@@ -2248,7 +2247,7 @@ static unsigned long *its_lpi_alloc(int nr_irqs, u32 *base, int *nr_ids)
 
 static void its_lpi_free(unsigned long *bitmap, u32 base, u32 nr_ids)
 {
-	WARN_ON(free_lpi_range(base, nr_ids));
+	free_lpi_range(base, nr_ids);
 	bitmap_free(bitmap);
 }
 
@@ -2349,7 +2348,9 @@ static int __init its_setup_lpi_prop_table(void)
 	pr_info("GICv3: using LPI property table @%pa\n",
 		&gic_rdists->prop_table_pa);
 
-	return its_lpi_init(lpi_id_bits);
+	its_lpi_init(lpi_id_bits);
+
+	return 0;
 }
 
 static const char *its_base_type_string[] = {

Re: [syzbot] [kernel?] WARNING in its_msi_teardown

[Marc Zyngier]

On Wed, 29 Jul 2026 01:08:31 +0100,
syzbot <syzbot+229d761b8a110e6de517@syzkaller.appspotmail.com> wrote:
> 
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    b66b0005b6ce Merge branches 'for-next/fixes' and 'for-next..
> 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=15f7d746580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=72c97575381cec47
> dashboard link: https://syzkaller.appspot.com/bug?extid=229d761b8a110e6de517
> compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
> userspace arch: arm64
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1667e09e580000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=17525fde580000
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/63e3226301fe/disk-b66b0005.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/b268844cbd22/vmlinux-b66b0005.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/9440dfc93d1e/Image-b66b0005.gz.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+229d761b8a110e6de517@syzkaller.appspotmail.com
> 
>  el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121
>  do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140
>  el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:736
>  el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755
>  el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594
> ------------[ cut here ]------------
> WARNING: drivers/irqchip/irq-gic-v3-its.c:2251 at its_lpi_free drivers/irqchip/irq-gic-v3-its.c:2251 [inline], CPU#0: syz.0.18/4916
> WARNING: drivers/irqchip/irq-gic-v3-its.c:2251 at its_msi_teardown+0x3a4/0x424 drivers/irqchip/irq-gic-v3-its.c:3644, CPU#0: syz.0.18/4916
> Modules linked in:
> CPU: 0 UID: 0 PID: 4916 Comm: syz.0.18 Not tainted syzkaller #0 PREEMPT 
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/02/2026
> pstate: 83400005 (Nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
> pc : its_lpi_free drivers/irqchip/irq-gic-v3-its.c:2251 [inline]
> pc : its_msi_teardown+0x3a4/0x424 drivers/irqchip/irq-gic-v3-its.c:3644
> lr : its_lpi_free drivers/irqchip/irq-gic-v3-its.c:2251 [inline]
> lr : its_msi_teardown+0x3a4/0x424 drivers/irqchip/irq-gic-v3-its.c:3644
> sp : ffff800098017560
> x29: ffff8000980175f0 x28: ffff0000cfc75930 x27: 1fffe00019f8eb26
> x26: 1fffe00019f8eb22 x25: ffff0000c13e1000 x24: dfff800000000000
> x23: ffff700013002eac x22: 00000000fffffff4 x21: ffff800098017580
> x20: ffff0000c1e07ce0 x19: ffff0000cfc75900 x18: 00000000ffffffff
> x17: 70202c31206c6176 x16: 0000000000000001 x15: 0000000000000000
> x14: 0000000000000000 x13: 0000000000000001 x12: 0000000000000000
> x11: 0000000000000000 x10: 0000000000000003 x9 : 0000000000000000
> x8 : 0000000000000000 x7 : 0000000000000000 x6 : 0000000000000000
> x5 : 00000000ffffffff x4 : 0000000000000cc0 x3 : ffff800081ba1c7c
> x2 : 00000000fffffff4 x1 : ffff0000cfb10000 x0 : 0000000000000000
> Call trace:
>  its_lpi_free drivers/irqchip/irq-gic-v3-its.c:2251 [inline] (P)
>  its_msi_teardown+0x3a4/0x424 drivers/irqchip/irq-gic-v3-its.c:3644 (P)
>  its_msi_teardown+0xa0/0xb8 drivers/irqchip/irq-gic-its-msi-parent.c:249

That's an allocation failure, caused by a fault injection. We end-up
leaking LPIs, but there isn't much we can do about that if we can't
allocate the correct tracking structure.

So yes, we WARN() about this, and carry on.

	M.

-- 
Without deviation from the norm, progress is not possible.

Re: [syzbot] [kernel?] WARNING in its_msi_teardown

[syzbot]

Hello,

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

Reported-by: syzbot+229d761b8a110e6de517@syzkaller.appspotmail.com
Tested-by: syzbot+229d761b8a110e6de517@syzkaller.appspotmail.com

Tested on:

commit:         365f9c7a Merge branches 'for-next/core' and 'for-next/..
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=1294b1b9580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=72c97575381cec47
dashboard link: https://syzkaller.appspot.com/bug?extid=229d761b8a110e6de517
compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
userspace arch: arm64
patch:          https://syzkaller.appspot.com/x/patch.diff?x=10b9a9b9580000

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