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Subject: Re: kernel BUG at arch/x86/mm/physaddr.c:LINE! (5)
To:     syzbot <syzbot+0bfda3ade1ee9288a1be@syzkaller.appspotmail.com>,
        daniel.vetter@ffwll.ch, gregkh@linuxfoundation.org,
        linux-kernel@vger.kernel.org, nico@fluxnic.net, sam@ravnborg.org,
        syzkaller-bugs@googlegroups.com
References: <000000000000479d8d05a49221b1@google.com>
From:   Jiri Slaby <jslaby@suse.com>
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Message-ID: <0c39d350-846a-eeda-f202-e36a53d495b2@suse.com>
Date:   Sat, 2 May 2020 08:49:12 +0200
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Sender: linux-kernel-owner@vger.kernel.org
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On 01. 05. 20, 10:40, syzbot wrote:
> Hello,
> 
> syzbot found the following crash on:
> 
> HEAD commit:    6a8b55ed Linux 5.7-rc3
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1447420fe00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=1ac152749c11ca54
> dashboard link: https://syzkaller.appspot.com/bug?extid=0bfda3ade1ee9288a1be
> compiler:       clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12db1b80100000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=15efcb80100000
> 
> The bug was bisected to:
> 
> commit 9a98e7a80f95378c9ee0c644705e3b5aa54745f1
> Author: Nicolas Pitre <nico@fluxnic.net>
> Date:   Sun Mar 29 02:25:11 2020 +0000
> 
>     vt: don't use kmalloc() for the unicode screen buffer
> 
> bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=16bb967fe00000
> final crash:    https://syzkaller.appspot.com/x/report.txt?x=15bb967fe00000
> console output: https://syzkaller.appspot.com/x/log.txt?x=11bb967fe00000
> 
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+0bfda3ade1ee9288a1be@syzkaller.appspotmail.com
> Fixes: 9a98e7a80f95 ("vt: don't use kmalloc() for the unicode screen buffer")
> 
> ------------[ cut here ]------------
> kernel BUG at arch/x86/mm/physaddr.c:28!
> invalid opcode: 0000 [#1] PREEMPT SMP KASAN
> CPU: 1 PID: 7061 Comm: syz-executor995 Not tainted 5.7.0-rc3-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> RIP: 0010:__phys_addr+0x10e/0x120 arch/x86/mm/physaddr.c:28
> Code: 6b 89 80 e1 07 38 c1 0f 8c 75 ff ff ff 48 c7 c7 85 a3 6b 89 e8 f3 a8 7d 00 e9 64 ff ff ff e8 b9 c5 3f 00 0f 0b e8 b2 c5 3f 00 <0f> 0b e8 ab c5 3f 00 0f 0b 66 0f 1f 84 00 00 00 00 00 53 48 89 fb
> RSP: 0018:ffffc900016579f8 EFLAGS: 00010093
> RAX: ffffffff81339bbe RBX: 0000000000000001 RCX: ffff88808dd5a340
> RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
> RBP: 00000000ffffffea R08: ffffffff81339b2c R09: ffffed1015d27074
> R10: ffffed1015d27074 R11: 0000000000000000 R12: ffffc900016c9000
> R13: dffffc0000000000 R14: 00004080016c9000 R15: ffffffff83fad568
> FS:  0000000001f5d880(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 000000000043e7d0 CR3: 0000000099a6c000 CR4: 00000000001406e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  virt_to_head_page include/linux/mm.h:833 [inline]
>  virt_to_cache mm/slab.h:474 [inline]
>  kfree+0x60/0x220 mm/slab.c:3749
>  vc_do_resize+0x738/0x1ce0 drivers/tty/vt/vt.c:1233
Of course, s/kfree/vfree/ there. NIcolas, could you fix this?

thanks,
-- 
js
suse labs