On Tue, Mar 5, 2024 at 11:16 AM Paul Moore <paul@xxxxxxxxxxxxxx> wrote: > > On Mon, Mar 4, 2024 at 9:32 PM Sam Sun <samsun1006219@xxxxxxxxx> wrote: > > On Tue, Mar 5, 2024 at 4:45 AM Paul Moore <paul@xxxxxxxxxxxxxx> wrote: > > > On Mon, Mar 4, 2024 at 3:11 PM Christian Göttsche > > > <cgzones@xxxxxxxxxxxxxx> wrote: > > > > On Mon, 4 Mar 2024 at 20:19, Paul Moore <paul@xxxxxxxxxxxxxx> wrote: > > > > > On Mon, Mar 4, 2024 at 9:08 AM Sam Sun <samsun1006219@xxxxxxxxx> wrote: > > > > > > > > > > > > Dear developers and maintainers, > > > > > > > > > > > > We encountered a warning in function sel_write_load(). It is tested on > > > > > > kernel 6.8.0-rc7. Bug report is listed below. > > > > > > > > > > > > ``` > > > > > > WARNING: CPU: 1 PID: 8109 at mm/vmalloc.c:3247 > > > > > > __vmalloc_node_range+0x10a0/0x1490 mm/vmalloc.c:3247 > > > > > > Modules linked in: > > > > > > CPU: 1 PID: 8109 Comm: syz-executor370 Not tainted 6.7.0-rc7 #1 > > > > > > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 > > > > > > RIP: 0010:__vmalloc_node_range+0x10a0/0x1490 mm/vmalloc.c:3247 > > > > > > Code: 65 48 2b 04 25 28 00 00 00 0f 85 98 02 00 00 48 81 c4 70 01 00 > > > > > > 00 4c 89 e0 5b 5d 41 5c 41 5d 41 5e 41 5f c3 e8 71 43 b7 ff 90 <0f> 0b > > > > > > 90 45 31 e4 eb a1 e8 63 43 b7 ff 48 8b 4c 24 40 31 f6 45 31 > > > > > > RSP: 0018:ffffc90002adf9c0 EFLAGS: 00010293 > > > > > > RAX: 0000000000000000 RBX: dffffc0000000000 RCX: ffffffff81cdc194 > > > > > > RDX: ffff888022124ec0 RSI: ffffffff81cdd16f RDI: 0000000000000007 > > > > > > RBP: 0000000000000000 R08: 0000000000000007 R09: 0000000000000000 > > > > > > R10: 0000000000000000 R11: 0000000000000001 R12: ffff888107373a48 > > > > > > R13: dffffc0000000000 R14: 0000000000000000 R15: ffffc90002adfec8 > > > > > > FS: 00005555560953c0(0000) GS:ffff888135c00000(0000) knlGS:0000000000000000 > > > > > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > > > > > CR2: 0000000020000010 CR3: 000000010503d000 CR4: 0000000000750ef0 > > > > > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > > > > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > > > > > PKRU: 55555554 > > > > > > Call Trace: > > > > > > <TASK> > > > > > > __vmalloc_node mm/vmalloc.c:3385 [inline] > > > > > > vmalloc+0x6b/0x80 mm/vmalloc.c:3418 > > > > > > sel_write_load+0x27f/0x19d0 security/selinux/selinuxfs.c:603 > > > > > > vfs_write+0x2a9/0xd80 fs/read_write.c:582 > > > > > > ksys_pwrite64 fs/read_write.c:699 [inline] > > > > > > __do_sys_pwrite64 fs/read_write.c:709 [inline] > > > > > > __se_sys_pwrite64 fs/read_write.c:706 [inline] > > > > > > __x64_sys_pwrite64+0x1f3/0x250 fs/read_write.c:706 > > > > > > do_syscall_x64 arch/x86/entry/common.c:52 [inline] > > > > > > do_syscall_64+0x40/0x110 arch/x86/entry/common.c:83 > > > > > > entry_SYSCALL_64_after_hwframe+0x63/0x6b > > > > > > RIP: 0033:0x7f40e7728f8d > > > > > > Code: 28 c3 e8 46 1e 00 00 66 0f 1f 44 00 00 f3 0f 1e fa 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:00007fff5bf39508 EFLAGS: 00000246 ORIG_RAX: 0000000000000012 > > > > > > RAX: ffffffffffffffda RBX: 00007fff5bf39708 RCX: 00007f40e7728f8d > > > > > > RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003 > > > > > > RBP: 0000000000000001 R08: 0000000000000000 R09: 00007fff5bf39708 > > > > > > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 > > > > > > R13: 00007fff5bf396f8 R14: 00007f40e77a6530 R15: 0000000000000001 > > > > > > </TASK> > > > > > > ``` > > > > > > > > > > > > The cause of this bug is that in sel_write_load(), parameter "count" > > > > > > is controlled by user, which could be zero. It is passed to vmalloc() > > > > > > as an argument. > > > > > > > > > > > > If you have any questions, please contact us. > > > > > > Reported by: Yue Sun <samsun1006219@xxxxxxxxx> > > > > > > Reported by: xingwei lee <xrivendell7@xxxxxxxxx> > > > > > > > > > > Everything appears to be working as expected, vmalloc() caught the > > > > > zero-length allocation request, emitted the warning, returned NULL to > > > > > sel_write_load(), and sel_write_load() handled the error condition > > > > > triggered by vmalloc(0) returning NULL. Did you see any unexpected > > > > > behavior beyond this warning message above? > > > > > > > > Probably because kernel warnings should not be reachable from > > > > userspace ... > > > > > > My question was asking if the reporter was seeing any unexpected > > > behavior *beyond* the warning message. I wanted to make sure they > > > weren't seeing anything else on their system that we should also take > > > into account. > > > > I didn't see any unexpected behavior beyond this warning message. You > > are right, everything appears to be working as expected. Like > > Christian said, I enabled kernel panic_on_warn config. I thought > > kernel warning was something worthy to report, but I was wrong. In > > future reports, I will check carefully to eliminate kernel warnings > > like "vmalloc zero" and "page size alloc too large" if they don't have > > unexpected behaviors. Sorry for wasting your time analyzing it, and > > thanks for pointing out my mistake! > > Thanks for the quick reply, I just wanted to make sure there wasn't > some other bug that was also triggered by passing a 0 count value; I'm > glad to hear there isn't. Regardless, there is likely some value in > protecting against 0 count/size values and I just posted a patch to do > just that (and some other misc cleanups to sel_write_load()). > > -- > paul-moore.com Maybe I should compile the kernel without panic_on_warn config, so that I can see how zero count / size values are passed through code and check if there is another potential threat. Thanks for your advice! Best Regards, Yue
