Messages in this thread | | | Date | Sun, 03 Jun 2018 16:36:02 -0700 | Subject | KASAN: use-after-free Read in skb_ensure_writable | From | syzbot <> |
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Hello,
syzbot found the following crash on:
HEAD commit: bcece5dc40b9 bpf: Change bpf_fib_lookup to return -EAFNOSU.. git tree: bpf-next console output: https://syzkaller.appspot.com/x/log.txt?x=10ee76b7800000 kernel config: https://syzkaller.appspot.com/x/.config?x=e4078980b886800c dashboard link: https://syzkaller.appspot.com/bug?extid=c8504affd4fdd0c1b626 compiler: gcc (GCC) 8.0.1 20180413 (experimental) syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=10d926df800000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1778c26f800000
IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+c8504affd4fdd0c1b626@syzkaller.appspotmail.com
random: sshd: uninitialized urandom read (32 bytes read) random: sshd: uninitialized urandom read (32 bytes read) random: sshd: uninitialized urandom read (32 bytes read) random: sshd: uninitialized urandom read (32 bytes read) ================================================================== BUG: KASAN: use-after-free in pskb_may_pull include/linux/skbuff.h:2108 [inline] BUG: KASAN: use-after-free in skb_ensure_writable+0x554/0x620 net/core/skbuff.c:5118 Read of size 4 at addr ffff8801b0b40fc0 by task syz-executor258/4479
CPU: 0 PID: 4479 Comm: syz-executor258 Not tainted 4.17.0-rc6+ #29 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 pskb_may_pull include/linux/skbuff.h:2108 [inline] skb_ensure_writable+0x554/0x620 net/core/skbuff.c:5118 __bpf_try_make_writable net/core/filter.c:1606 [inline] bpf_try_make_writable net/core/filter.c:1612 [inline] ____bpf_l3_csum_replace net/core/filter.c:1774 [inline] bpf_l3_csum_replace+0x8c/0x4d0 net/core/filter.c:1765
The buggy address belongs to the page: page:ffffea0006c2d000 count:0 mapcount:0 mapping:0000000000000000 index:0x0 flags: 0x2fffc0000000000() raw: 02fffc0000000000 0000000000000000 0000000000000000 00000000ffffffff raw: ffffea00075ea760 ffffea0006c39660 ffff8801b5848738 0000000000000000 page dumped because: kasan: bad access detected
Memory state around the buggy address: ffff8801b0b40e80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff8801b0b40f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff > ffff8801b0b40f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ^ ffff8801b0b41000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8801b0b41080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================
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