[PATCH] drm/syncobj: Prevent overflow and large kmalloc in array_find()

[PATCH] drm/syncobj: Prevent overflow and large kmalloc in array_find()

[Madhur Kumar]

#syz test

Signed-off-by: Madhur Kumar <madhurkumar004@gmail.com>
---
 drivers/gpu/drm/drm_syncobj.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
index e1b0fa4000cd..f322b38ec251 100644
--- a/drivers/gpu/drm/drm_syncobj.c
+++ b/drivers/gpu/drm/drm_syncobj.c
@@ -1293,6 +1293,13 @@ static int drm_syncobj_array_find(struct drm_file *file_private,
 	uint32_t i, *handles;
 	struct drm_syncobj **syncobjs;
 	int ret;
+	size_t size;
+
+	if (check_mul_overflow(count_handles, sizeof(*handles), &size))
+		return -EOVERFLOW;
+
+	if (size > KMALLOC_MAX_SIZE)
+		return -ERANGE;
 
 	handles = kmalloc_array(count_handles, sizeof(*handles), GFP_KERNEL);
 	if (handles == NULL)
-- 
2.52.0

Re: [syzbot] [dri?] WARNING in drm_syncobj_array_find

[syzbot]

Hello,

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

Reported-by: syzbot+95416f957d84e858b377@syzkaller.appspotmail.com
Tested-by: syzbot+95416f957d84e858b377@syzkaller.appspotmail.com

Tested on:

commit:         765e56e4 Merge tag 'v6.18rc7-SMB-client-fix' of git://..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1696e57c580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=4a9a49032e9d8959
dashboard link: https://syzkaller.appspot.com/bug?extid=95416f957d84e858b377
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=155f6f42580000

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

[syzbot] [dri?] WARNING in drm_syncobj_array_find

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    0468be89b3fa Merge tag 'iommu-updates-v6.6' of git://git.k..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13571367a80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=39744401c57166fc
dashboard link: https://syzkaller.appspot.com/bug?extid=95416f957d84e858b377
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=111c39a8680000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1267d83fa80000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7bc7510fe41f/non_bootable_disk-0468be89.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/7feba36779de/vmlinux-0468be89.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b1cdc0506491/bzImage-0468be89.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+95416f957d84e858b377@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: CPU: 2 PID: 5141 at mm/page_alloc.c:4415 __alloc_pages+0x3ab/0x4a0 mm/page_alloc.c:4415
Modules linked in:
CPU: 2 PID: 5141 Comm: syz-executor127 Not tainted 6.5.0-syzkaller-10885-g0468be89b3fa #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:__alloc_pages+0x3ab/0x4a0 mm/page_alloc.c:4415
Code: ff ff 00 0f 84 2f fe ff ff 80 ce 01 e9 27 fe ff ff 83 fe 0a 0f 86 3a fd ff ff 80 3d c9 37 e6 0c 00 75 09 c6 05 c0 37 e6 0c 01 <0f> 0b 45 31 f6 e9 97 fe ff ff e8 b6 10 9e ff 84 c0 0f 85 8a fe ff
RSP: 0018:ffffc900030b7a18 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000040cc0 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000016 RDI: 0000000000040cc0
RBP: 1ffff92000616f44 R08: 0000000000000005 R09: 0000000000000000
R10: 00000000ffffff1f R11: 0000000000000000 R12: 0000000000000016
R13: 0000000000000000 R14: ffffffff84b4e215 R15: ffff888013722000
FS:  00005555555a4380(0000) GS:ffff88806b800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000200001c0 CR3: 000000002accd000 CR4: 0000000000350ee0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __alloc_pages_node include/linux/gfp.h:237 [inline]
 alloc_pages_node include/linux/gfp.h:260 [inline]
 __kmalloc_large_node+0x87/0x1c0 mm/slab_common.c:1164
 __do_kmalloc_node mm/slab_common.c:1011 [inline]
 __kmalloc.cold+0xb/0xe0 mm/slab_common.c:1036
 kmalloc_array include/linux/slab.h:636 [inline]
 drm_syncobj_array_find+0x35/0x3c0 drivers/gpu/drm/drm_syncobj.c:1246
 drm_syncobj_timeline_signal_ioctl+0x21f/0x860 drivers/gpu/drm/drm_syncobj.c:1533
 drm_ioctl_kernel+0x280/0x4c0 drivers/gpu/drm/drm_ioctl.c:789
 drm_ioctl+0x5cb/0xbf0 drivers/gpu/drm/drm_ioctl.c:892
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:871 [inline]
 __se_sys_ioctl fs/ioctl.c:857 [inline]
 __x64_sys_ioctl+0x18f/0x210 fs/ioctl.c:857
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7ff62d53f129
Code: 48 83 c4 28 c3 e8 37 17 00 00 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe7c669ea8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007ffe7c66a078 RCX: 00007ff62d53f129
RDX: 0000000020000500 RSI: 00000000c01864cd RDI: 0000000000000003
RBP: 00007ff62d5b2610 R08: 0023647261632f69 R09: 00007ffe7c66a078
R10: 000000000000001f R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffe7c66a068 R14: 0000000000000001 R15: 0000000000000001
 </TASK>


---
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