Messages in this thread | | | From | Dmitry Vyukov <> | Date | Fri, 27 Apr 2018 17:19:07 +0200 | Subject | Re: KASAN: use-after-free Read in process_preds |
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On Fri, Apr 27, 2018 at 7:30 AM, syzbot <syzbot+b6fc33dcecb65cd8ff80@syzkaller.appspotmail.com> wrote: > Hello, > > syzbot hit the following crash on bpf-next commit > 5d1365940a68dd57b031b6e3c07d7d451cd69daf (Thu Apr 12 18:09:05 2018 +0000) > Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net > syzbot dashboard link: > https://syzkaller.appspot.com/bug?extid=b6fc33dcecb65cd8ff80 > > Unfortunately, I don't have any reproducer for this crash yet. > Raw console output: > https://syzkaller.appspot.com/x/log.txt?id=4606019153952768 > Kernel config: > https://syzkaller.appspot.com/x/.config?id=-5947642240294114534 > compiler: gcc (GCC) 8.0.1 20180413 (experimental) > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+b6fc33dcecb65cd8ff80@syzkaller.appspotmail.com > It will help syzbot understand when the bug is fixed. See footer for > details. > If you forward the report, please keep this part and the footer. > > ================================================================== > BUG: KASAN: use-after-free in predicate_parse > kernel/trace/trace_events_filter.c:563 [inline] > BUG: KASAN: use-after-free in process_preds+0x197f/0x19b0 > kernel/trace/trace_events_filter.c:1505 > Read of size 4 at addr ffff8801b9832ce4 by task syz-executor0/28463 > > CPU: 0 PID: 28463 Comm: syz-executor0 Not tainted 4.16.0+ #2 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > Call Trace: > __dump_stack lib/dump_stack.c:77 [inline] > dump_stack+0x1b9/0x294 lib/dump_stack.c:113 > print_address_description+0x6c/0x20b mm/kasan/report.c:256 > kasan_report_error mm/kasan/report.c:354 [inline] > kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412 > __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:432 > predicate_parse kernel/trace/trace_events_filter.c:563 [inline] > process_preds+0x197f/0x19b0 kernel/trace/trace_events_filter.c:1505 > create_filter+0x1a8/0x370 kernel/trace/trace_events_filter.c:1714 > ftrace_profile_set_filter+0x109/0x2b0 > kernel/trace/trace_events_filter.c:2042 > perf_event_set_filter+0x248/0x1230 kernel/events/core.c:9064 > _perf_ioctl+0x84c/0x15e0 kernel/events/core.c:5056 > perf_ioctl+0x59/0x80 kernel/events/core.c:5107 > vfs_ioctl fs/ioctl.c:46 [inline] > file_ioctl fs/ioctl.c:500 [inline] > do_vfs_ioctl+0x1cf/0x16a0 fs/ioctl.c:684 > ksys_ioctl+0xa9/0xd0 fs/ioctl.c:701 > SYSC_ioctl fs/ioctl.c:708 [inline] > SyS_ioctl+0x24/0x30 fs/ioctl.c:706 > do_syscall_64+0x29e/0x9d0 arch/x86/entry/common.c:287 > entry_SYSCALL_64_after_hwframe+0x42/0xb7 > RIP: 0033:0x455329 > RSP: 002b:00007f14b2c73c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 > RAX: ffffffffffffffda RBX: 00007f14b2c746d4 RCX: 0000000000455329 > RDX: 0000000020000040 RSI: 0000000040082406 RDI: 0000000000000013 > RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff > R13: 0000000000000291 R14: 00000000006f6e38 R15: 0000000000000000 > > Allocated by task 2370: > save_stack+0x43/0xd0 mm/kasan/kasan.c:448 > set_track mm/kasan/kasan.c:460 [inline] > kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553 > kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490 > kmem_cache_alloc+0x12e/0x760 mm/slab.c:3554 > getname_flags+0xd0/0x5a0 fs/namei.c:140 > getname+0x19/0x20 fs/namei.c:211 > do_sys_open+0x39a/0x740 fs/open.c:1087 > SYSC_open fs/open.c:1111 [inline] > SyS_open+0x2d/0x40 fs/open.c:1106 > do_syscall_64+0x29e/0x9d0 arch/x86/entry/common.c:287 > entry_SYSCALL_64_after_hwframe+0x42/0xb7 > > Freed by task 2370: > save_stack+0x43/0xd0 mm/kasan/kasan.c:448 > set_track mm/kasan/kasan.c:460 [inline] > __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521 > kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 > __cache_free mm/slab.c:3498 [inline] > kmem_cache_free+0x86/0x2d0 mm/slab.c:3756 > putname+0xf2/0x130 fs/namei.c:261 > do_sys_open+0x554/0x740 fs/open.c:1102 > SYSC_open fs/open.c:1111 [inline] > SyS_open+0x2d/0x40 fs/open.c:1106 > do_syscall_64+0x29e/0x9d0 arch/x86/entry/common.c:287 > entry_SYSCALL_64_after_hwframe+0x42/0xb7 > > The buggy address belongs to the object at ffff8801b9832340 > which belongs to the cache names_cache of size 4096 > The buggy address is located 2468 bytes inside of > 4096-byte region [ffff8801b9832340, ffff8801b9833340) > The buggy address belongs to the page: > page:ffffea0006e60c80 count:1 mapcount:0 mapping:ffff8801b9832340 index:0x0 > compound_mapcount: 0 > flags: 0x2fffc0000008100(slab|head) > raw: 02fffc0000008100 ffff8801b9832340 0000000000000000 0000000100000001 > raw: ffffea000743eca0 ffffea0006628f20 ffff8801dad86dc0 0000000000000000 > page dumped because: kasan: bad access detected > > Memory state around the buggy address: > ffff8801b9832b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ffff8801b9832c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >> >> ffff8801b9832c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > ^ > ffff8801b9832d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ffff8801b9832d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ==================================================================
Here is a repro:
// autogenerated by syzkaller (http://github.com/google/syzkaller)
#define _GNU_SOURCE #include <endian.h> #include <stdint.h> #include <string.h> #include <sys/syscall.h> #include <unistd.h>
#define BITMASK_LEN(type, bf_len) (type)((1ull << (bf_len)) - 1)
#define BITMASK_LEN_OFF(type, bf_off, bf_len) \ (type)(BITMASK_LEN(type, (bf_len)) << (bf_off))
#define STORE_BY_BITMASK(type, addr, val, bf_off, bf_len) \ if ((bf_off) == 0 && (bf_len) == 0) { \ *(type*)(addr) = (type)(val); \ } else { \ type new_val = *(type*)(addr); \ new_val &= ~BITMASK_LEN_OFF(type, (bf_off), (bf_len)); \ new_val |= ((type)(val)&BITMASK_LEN(type, (bf_len))) << (bf_off); \ *(type*)(addr) = new_val; \ }
uint64_t r[1] = {0xffffffffffffffff}; void loop() { long res = 0; *(uint32_t*)0x2025c000 = 2; *(uint32_t*)0x2025c004 = 0x78; *(uint8_t*)0x2025c008 = 0xe2; *(uint8_t*)0x2025c009 = 0; *(uint8_t*)0x2025c00a = 0; *(uint8_t*)0x2025c00b = 0; *(uint32_t*)0x2025c00c = 0; *(uint64_t*)0x2025c010 = 0; *(uint64_t*)0x2025c018 = 0; *(uint64_t*)0x2025c020 = 0; STORE_BY_BITMASK(uint64_t, 0x2025c028, 0, 0, 1); STORE_BY_BITMASK(uint64_t, 0x2025c028, 0, 1, 1); STORE_BY_BITMASK(uint64_t, 0x2025c028, 0, 2, 1); STORE_BY_BITMASK(uint64_t, 0x2025c028, 0, 3, 1); STORE_BY_BITMASK(uint64_t, 0x2025c028, 0, 4, 1); STORE_BY_BITMASK(uint64_t, 0x2025c028, 0, 5, 1); STORE_BY_BITMASK(uint64_t, 0x2025c028, 0, 6, 1); STORE_BY_BITMASK(uint64_t, 0x2025c028, 0, 7, 1); STORE_BY_BITMASK(uint64_t, 0x2025c028, 0, 8, 1); STORE_BY_BITMASK(uint64_t, 0x2025c028, 0, 9, 1); STORE_BY_BITMASK(uint64_t, 0x2025c028, 0, 10, 1); STORE_BY_BITMASK(uint64_t, 0x2025c028, 0, 11, 1); STORE_BY_BITMASK(uint64_t, 0x2025c028, 0, 12, 1); STORE_BY_BITMASK(uint64_t, 0x2025c028, 0, 13, 1); STORE_BY_BITMASK(uint64_t, 0x2025c028, 0, 14, 1); STORE_BY_BITMASK(uint64_t, 0x2025c028, 0, 15, 2); STORE_BY_BITMASK(uint64_t, 0x2025c028, 0, 17, 1); STORE_BY_BITMASK(uint64_t, 0x2025c028, 0, 18, 1); STORE_BY_BITMASK(uint64_t, 0x2025c028, 0, 19, 1); STORE_BY_BITMASK(uint64_t, 0x2025c028, 0, 20, 1); STORE_BY_BITMASK(uint64_t, 0x2025c028, 0, 21, 1); STORE_BY_BITMASK(uint64_t, 0x2025c028, 0, 22, 1); STORE_BY_BITMASK(uint64_t, 0x2025c028, 0, 23, 1); STORE_BY_BITMASK(uint64_t, 0x2025c028, 0, 24, 1); STORE_BY_BITMASK(uint64_t, 0x2025c028, 0, 25, 1); STORE_BY_BITMASK(uint64_t, 0x2025c028, 0, 26, 1); STORE_BY_BITMASK(uint64_t, 0x2025c028, 0, 27, 1); STORE_BY_BITMASK(uint64_t, 0x2025c028, 0, 28, 1); STORE_BY_BITMASK(uint64_t, 0x2025c028, 0, 29, 35); *(uint32_t*)0x2025c030 = 0; *(uint32_t*)0x2025c034 = 0; *(uint64_t*)0x2025c038 = 0x20000000; *(uint64_t*)0x2025c040 = 0; *(uint64_t*)0x2025c048 = 0; *(uint64_t*)0x2025c050 = 0; *(uint32_t*)0x2025c058 = 0; *(uint32_t*)0x2025c05c = 0; *(uint64_t*)0x2025c060 = 0; *(uint32_t*)0x2025c068 = 0; *(uint16_t*)0x2025c06c = 0; *(uint16_t*)0x2025c06e = 0; res = syscall(__NR_perf_event_open, 0x2025c000, 0, -1, -1, 0); if (res != -1) r[0] = res; memcpy((void*)0x20000100, "!", 2); syscall(__NR_ioctl, r[0], 0x40082406, 0x20000100); }
int main() { syscall(__NR_mmap, 0x20000000, 0x1000000, 3, 0x32, -1, 0); loop(); return 0; }
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