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006d021491bc7-68be6722936mr7612252eaf.25.1776144361433; Mon, 13 Apr 2026 22:26:01 -0700 (PDT) Date: Mon, 13 Apr 2026 22:26:01 -0700 In-Reply-To: <20260414050005.1782-1-hdanton@sina.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <69ddcfe9.a00a0220.475f0.0035.GAE@google.com> Subject: Re: [syzbot] [dri?] KASAN: slab-use-after-free Read in drm_gem_object_release_handle From: syzbot To: hdanton@sina.com, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot has tested the proposed patch but the reproducer is still triggering an issue: KFENCE: use-after-free read in drm_gem_object_release_handle ================================================================== BUG: KFENCE: use-after-free read in drm_gem_object_release_handle+0x47/0x1e0 drivers/gpu/drm/drm_gem.c:374 Use-after-free read at 0xffff88823be98e88 (in kfence-#75): drm_gem_object_release_handle+0x47/0x1e0 drivers/gpu/drm/drm_gem.c:374 drm_gem_object_release_idr_handle+0x69/0x80 drivers/gpu/drm/drm_gem.c:403 idr_for_each+0x1c6/0x2a0 lib/idr.c:210 drm_gem_release+0x28/0x40 drivers/gpu/drm/drm_gem.c:1105 drm_file_free+0x729/0xa00 drivers/gpu/drm/drm_file.c:261 drm_close_helper drivers/gpu/drm/drm_file.c:290 [inline] drm_release+0x2de/0x3f0 drivers/gpu/drm/drm_file.c:438 __fput+0x44f/0xa60 fs/file_table.c:510 task_work_run+0x1d9/0x270 kernel/task_work.c:233 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] __exit_to_user_mode_loop kernel/entry/common.c:67 [inline] exit_to_user_mode_loop+0xed/0x480 kernel/entry/common.c:98 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline] do_syscall_64+0x33e/0xf80 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f kfence-#75: 0xffff88823be98c00-0xffff88823be98ee7, size=744, cache=kmalloc-1k allocated by task 6583 on cpu 0 at 133.209896s (0.096709s ago): kmalloc_noprof include/linux/slab.h:950 [inline] kzalloc_noprof include/linux/slab.h:1188 [inline] __drm_gem_shmem_create+0xc4/0x2e0 drivers/gpu/drm/drm_gem_shmem_helper.c:130 drm_gem_shmem_create drivers/gpu/drm/drm_gem_shmem_helper.c:157 [inline] drm_gem_shmem_create_with_handle drivers/gpu/drm/drm_gem_shmem_helper.c:460 [inline] drm_gem_shmem_dumb_create+0x72/0x120 drivers/gpu/drm/drm_gem_shmem_helper.c:549 drm_mode_create_dumb drivers/gpu/drm/drm_dumb_buffers.c:227 [inline] drm_mode_create_dumb_ioctl+0x2bd/0x340 drivers/gpu/drm/drm_dumb_buffers.c:236 drm_ioctl_kernel+0x2df/0x3b0 drivers/gpu/drm/drm_ioctl.c:804 drm_ioctl+0x6ba/0xb80 drivers/gpu/drm/drm_ioctl.c:901 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f freed by task 6585 on cpu 1 at 133.211010s (0.147010s ago): drm_gem_handle_delete+0x7b/0xb0 drivers/gpu/drm/drm_gem.c:430 drm_ioctl_kernel+0x2df/0x3b0 drivers/gpu/drm/drm_ioctl.c:804 drm_ioctl+0x6ba/0xb80 drivers/gpu/drm/drm_ioctl.c:901 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f CPU: 1 UID: 0 PID: 6581 Comm: syz.1.67 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026 RIP: 0010:drm_gem_object_release_handle+0x47/0x1e0 drivers/gpu/drm/drm_gem.c:374 Code: 5f 6c 62 fc 4d 85 f6 0f 84 9e 00 00 00 4c 8d bb 88 02 00 00 4c 89 f8 48 c1 e8 03 42 80 3c 28 00 74 08 4c 89 ff e8 59 c1 cc fc <4d> 8b 3f 49 83 c7 10 4c 89 f8 48 c1 e8 03 42 80 3c 28 00 74 08 4c RSP: 0018:ffffc90003f27ad8 EFLAGS: 00010246 RAX: 1ffff110477d31d1 RBX: ffff88823be98c00 RCX: ffff888054fa1e80 RDX: 0000000000000000 RSI: ffff88823be98c00 RDI: 0000000000000080 RBP: 0000000000000080 R08: ffff8880321950e3 R09: 1ffff11006432a1c R10: dffffc0000000000 R11: ffffed1006432a1d R12: ffff8880321950e0 R13: dffffc0000000000 R14: ffff888032195000 R15: ffff88823be98e88 FS: 000055557167a500(0000) GS:ffff88812554b000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffff88823be98e88 CR3: 000000006dd68000 CR4: 00000000003526f0 Call Trace: drm_gem_object_release_idr_handle+0x69/0x80 drivers/gpu/drm/drm_gem.c:403 idr_for_each+0x1c6/0x2a0 lib/idr.c:210 drm_gem_release+0x28/0x40 drivers/gpu/drm/drm_gem.c:1105 drm_file_free+0x729/0xa00 drivers/gpu/drm/drm_file.c:261 drm_close_helper drivers/gpu/drm/drm_file.c:290 [inline] drm_release+0x2de/0x3f0 drivers/gpu/drm/drm_file.c:438 __fput+0x44f/0xa60 fs/file_table.c:510 task_work_run+0x1d9/0x270 kernel/task_work.c:233 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] __exit_to_user_mode_loop kernel/entry/common.c:67 [inline] exit_to_user_mode_loop+0xed/0x480 kernel/entry/common.c:98 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline] do_syscall_64+0x33e/0xf80 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f246c99c819 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffd35630618 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4 RAX: 0000000000000000 RBX: 00007ffd35630700 RCX: 00007f246c99c819 RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003 RBP: 000000000002082e R08: 0000000000000001 R09: 0000000000000000 R10: 0000001b32820000 R11: 0000000000000246 R12: 00007ffd35630740 R13: 00007f246cc1609c R14: 0000000000020866 R15: 00007f246cc16090 ================================================================== ---------------- Code disassembly (best guess), 3 bytes skipped: 0: fc cld 1: 4d 85 f6 test %r14,%r14 4: 0f 84 9e 00 00 00 je 0xa8 a: 4c 8d bb 88 02 00 00 lea 0x288(%rbx),%r15 11: 4c 89 f8 mov %r15,%rax 14: 48 c1 e8 03 shr $0x3,%rax 18: 42 80 3c 28 00 cmpb $0x0,(%rax,%r13,1) 1d: 74 08 je 0x27 1f: 4c 89 ff mov %r15,%rdi 22: e8 59 c1 cc fc call 0xfcccc180 * 27: 4d 8b 3f mov (%r15),%r15 <-- trapping instruction 2a: 49 83 c7 10 add $0x10,%r15 2e: 4c 89 f8 mov %r15,%rax 31: 48 c1 e8 03 shr $0x3,%rax 35: 42 80 3c 28 00 cmpb $0x0,(%rax,%r13,1) 3a: 74 08 je 0x44 3c: 4c rex.WR Tested on: commit: d60bc140 Merge tag 'pwrseq-updates-for-v7.1-rc1' of gi.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=157e7cd2580000 kernel config: https://syzkaller.appspot.com/x/.config?x=85bd86f990609a1 dashboard link: https://syzkaller.appspot.com/bug?extid=b2e951687503f32f74ce compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8 patch: https://syzkaller.appspot.com/x/patch.diff?x=12673036580000