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Date: Tue, 28 May 2024 09:49:20 -0700
Message-ID: <0000000000004d74b30619866a7f@google.com>
Subject: [syzbot] [mm?] UBSAN: shift-out-of-bounds in try_to_shrink_lruvec
From: syzbot <syzbot+17416257cb95200cba44@syzkaller.appspotmail.com>
To: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, 
	linux-mm@kvack.org, syzkaller-bugs@googlegroups.com
Content-Type: text/plain; charset="UTF-8"

Hello,

syzbot found the following issue on:

HEAD commit:    6dc544b66971 Add linux-next specific files for 20240528
git tree:       linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=146d3f84980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=6a363b35598e573d
dashboard link: https://syzkaller.appspot.com/bug?extid=17416257cb95200cba44
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11e41b72980000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=15f3d2d2980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/334699ab67f8/disk-6dc544b6.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4ca32b2218ce/vmlinux-6dc544b6.xz
kernel image: https://storage.googleapis.com/syzbot-assets/400bc5f019b3/bzImage-6dc544b6.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+17416257cb95200cba44@syzkaller.appspotmail.com

------------[ cut here ]------------
UBSAN: shift-out-of-bounds in mm/vmscan.c:4715:21
shift exponent -1 is negative
CPU: 1 PID: 5094 Comm: syz-executor177 Not tainted 6.10.0-rc1-next-20240528-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 ubsan_epilogue lib/ubsan.c:231 [inline]
 __ubsan_handle_shift_out_of_bounds+0x3c8/0x420 lib/ubsan.c:468
 get_nr_to_scan mm/vmscan.c:4715 [inline]
 try_to_shrink_lruvec+0xa99/0xbb0 mm/vmscan.c:4761
 lru_gen_shrink_lruvec mm/vmscan.c:4908 [inline]
 shrink_lruvec+0x554/0x3070 mm/vmscan.c:5685
 shrink_node_memcgs mm/vmscan.c:5921 [inline]
 shrink_node+0xb17/0x4150 mm/vmscan.c:5961
 shrink_zones mm/vmscan.c:6205 [inline]
 do_try_to_free_pages+0x789/0x1cb0 mm/vmscan.c:6267
 try_to_free_mem_cgroup_pages+0x48f/0xb10 mm/vmscan.c:6598
 try_charge_memcg+0x704/0x1850 mm/memcontrol.c:2946
 try_charge mm/memcontrol.c:3094 [inline]
 charge_memcg+0xa2/0x160 mm/memcontrol.c:7532
 __mem_cgroup_charge+0x27/0x80 mm/memcontrol.c:7547
 mem_cgroup_charge include/linux/memcontrol.h:686 [inline]
 shmem_alloc_and_add_folio+0x44b/0xbd0 mm/shmem.c:1663
 shmem_get_folio_gfp+0x82d/0x1f50 mm/shmem.c:2041
 shmem_read_folio_gfp+0xd6/0x170 mm/shmem.c:4944
 drm_gem_get_pages+0x21b/0xe50 drivers/gpu/drm/drm_gem.c:568
 drm_gem_shmem_get_pages+0xdd/0x290 drivers/gpu/drm/drm_gem_shmem_helper.c:177
 drm_gem_shmem_vmap+0x2ba/0x630 drivers/gpu/drm/drm_gem_shmem_helper.c:335
 drm_gem_vmap drivers/gpu/drm/drm_gem.c:1205 [inline]
 drm_gem_vmap_unlocked+0x103/0x1d0 drivers/gpu/drm/drm_gem.c:1247
 drm_gem_fb_vmap+0xa6/0x810 drivers/gpu/drm/drm_gem_framebuffer_helper.c:365
 drm_atomic_helper_prepare_planes+0x2b2/0xb50 drivers/gpu/drm/drm_atomic_helper.c:2601
 drm_atomic_helper_commit+0x18b/0x9f0 drivers/gpu/drm/drm_atomic_helper.c:2029
 drm_atomic_commit+0x2ac/0x310 drivers/gpu/drm/drm_atomic.c:1514
 drm_atomic_helper_update_plane+0x238/0x3a0 drivers/gpu/drm/drm_atomic_helper.c:3190
 drm_mode_cursor_universal drivers/gpu/drm/drm_plane.c:1221 [inline]
 drm_mode_cursor_common+0xd68/0x1570 drivers/gpu/drm/drm_plane.c:1280
 drm_mode_cursor_ioctl+0xe1/0x160 drivers/gpu/drm/drm_plane.c:1330
 drm_ioctl_kernel+0x33a/0x440 drivers/gpu/drm/drm_ioctl.c:744
 drm_ioctl+0x611/0xad0 drivers/gpu/drm/drm_ioctl.c:841
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:907 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:893
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f06b4225999
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 61 18 00 00 90 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:00007fff29e89738 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f06b4225999
RDX: 0000000020000340 RSI: 00000000c01c64a3 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0023647261632f69 R11: 0000000000000246 R12: 00007f06b426f036
R13: 00007fff29e89770 R14: 00007fff29e897b0 R15: 0000000000000000
 </TASK>
---[ end trace ]---


---
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