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(version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 16 Jan 2024 10:29:17 -0800 (PST) Message-ID: <487a298c-710d-4c04-8901-da584e1b3038@kernel.dk> Date: Tue, 16 Jan 2024 11:29:17 -0700 Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [syzbot] [block?] BUG: unable to handle kernel NULL pointer dereference in __bio_release_pages Content-Language: en-US From: Jens Axboe To: syzbot , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, Matthew Wilcox References: <000000000000dbe2f2060f0d2781@google.com> <4bd438c0-75b8-4e28-939c-954716df7563@kernel.dk> In-Reply-To: <4bd438c0-75b8-4e28-939c-954716df7563@kernel.dk> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 1/16/24 11:00 AM, Jens Axboe wrote: > On 1/16/24 2:57 AM, syzbot wrote: >> Hello, >> >> syzbot found the following issue on: >> >> HEAD commit: 052d534373b7 Merge tag 'exfat-for-6.8-rc1' of git://git.ke.. >> git tree: upstream >> console output: https://syzkaller.appspot.com/x/log.txt?x=17957913e80000 >> kernel config: https://syzkaller.appspot.com/x/.config?x=9603f9823d535d97 >> dashboard link: https://syzkaller.appspot.com/bug?extid=004c1e0fced2b4bc3dcc >> compiler: aarch64-linux-gnu-gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40 >> userspace arch: arm64 >> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13529733e80000 >> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=166850dde80000 >> >> Downloadable assets: >> disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/384ffdcca292/non_bootable_disk-052d5343.raw.xz >> vmlinux: https://storage.googleapis.com/syzbot-assets/74cc52d4cc15/vmlinux-052d5343.xz >> kernel image: https://storage.googleapis.com/syzbot-assets/a2da7e6a234c/Image-052d5343.gz.xz >> >> IMPORTANT: if you fix the issue, please add the following tag to the commit: >> Reported-by: syzbot+004c1e0fced2b4bc3dcc@syzkaller.appspotmail.com >> >> Unable to handle kernel paging request at virtual address dfff800000000001 >> KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f] >> Mem abort info: >> ESR = 0x0000000096000005 >> EC = 0x25: DABT (current EL), IL = 32 bits >> SET = 0, FnV = 0 >> EA = 0, S1PTW = 0 >> FSC = 0x05: level 1 translation fault >> Data abort info: >> ISV = 0, ISS = 0x00000005, ISS2 = 0x00000000 >> CM = 0, WnR = 0, TnD = 0, TagAccess = 0 >> GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 >> [dfff800000000001] address between user and kernel address ranges >> Internal error: Oops: 0000000096000005 [#1] PREEMPT SMP >> Modules linked in: >> CPU: 1 PID: 3139 Comm: syz-executor303 Not tainted 6.7.0-syzkaller-09928-g052d534373b7 #0 >> Hardware name: linux,dummy-virt (DT) >> pstate: 10000005 (nzcV daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) >> pc : _compound_head include/linux/page-flags.h:247 [inline] >> pc : bio_first_folio include/linux/bio.h:289 [inline] >> pc : __bio_release_pages+0x100/0x73c block/bio.c:1153 >> lr : bio_release_pages include/linux/bio.h:508 [inline] >> lr : blkdev_bio_end_io+0x2a0/0x3f0 block/fops.c:157 >> sp : ffff800089a375e0 >> x29: ffff800089a375e0 x28: 1fffe0000162e879 x27: ffff00000b1743c0 >> x26: ffff00000b1743c8 x25: 000000000000000a x24: 1fffe000015a9e12 >> x23: ffff00000ad4f094 x22: ffff00000f496600 x21: 1fffe0000162e87a >> x20: 0000000000000004 x19: 0000000000000000 x18: ffff00000b174432 >> x17: ffff00000b174438 x16: ffff00000f948008 x15: 1fffe0000162e886 >> x14: ffff00000b1743d4 x13: 00000000f1f1f1f1 x12: ffff6000015a9e13 >> x11: 1fffe000015a9e12 x10: ffff6000015a9e12 x9 : dfff800000000000 >> x8 : ffff00000b1743d4 x7 : 0000000041b58ab3 x6 : 1ffff00011346ed0 >> x5 : ffff700011346ed0 x4 : 00000000f1f1f1f1 x3 : 000000000000f1f1 >> x2 : 0000000000000001 x1 : dfff800000000000 x0 : 0000000000000008 >> Call trace: >> _compound_head include/linux/page-flags.h:247 [inline] >> bio_first_folio include/linux/bio.h:289 [inline] >> __bio_release_pages+0x100/0x73c block/bio.c:1153 >> bio_release_pages include/linux/bio.h:508 [inline] >> blkdev_bio_end_io+0x2a0/0x3f0 block/fops.c:157 >> bio_endio+0x4a4/0x618 block/bio.c:1608 >> __blkdev_direct_IO block/fops.c:213 [inline] >> blkdev_direct_IO.part.0+0xf08/0x13c0 block/fops.c:379 >> blkdev_direct_IO block/fops.c:370 [inline] >> blkdev_direct_write block/fops.c:648 [inline] >> blkdev_write_iter+0x430/0x91c block/fops.c:706 >> call_write_iter include/linux/fs.h:2085 [inline] >> do_iter_readv_writev+0x194/0x298 fs/read_write.c:741 >> vfs_writev+0x244/0x684 fs/read_write.c:971 >> do_pwritev+0x15c/0x1e0 fs/read_write.c:1072 >> __do_sys_pwritev2 fs/read_write.c:1131 [inline] >> __se_sys_pwritev2 fs/read_write.c:1122 [inline] >> __arm64_sys_pwritev2+0xac/0x120 fs/read_write.c:1122 >> __invoke_syscall arch/arm64/kernel/syscall.c:37 [inline] >> invoke_syscall+0x6c/0x258 arch/arm64/kernel/syscall.c:51 >> el0_svc_common.constprop.0+0xac/0x230 arch/arm64/kernel/syscall.c:136 >> do_el0_svc+0x40/0x58 arch/arm64/kernel/syscall.c:155 >> el0_svc+0x58/0x140 arch/arm64/kernel/entry-common.c:678 >> el0t_64_sync_handler+0x100/0x12c arch/arm64/kernel/entry-common.c:696 >> el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:595 >> Code: d2d00001 f2fbffe1 91002260 d343fc02 (38e16841) >> ---[ end trace 0000000000000000 ]--- >> ---------------- >> Code disassembly (best guess): >> 0: d2d00001 mov x1, #0x800000000000 // #140737488355328 >> 4: f2fbffe1 movk x1, #0xdfff, lsl #48 >> 8: 91002260 add x0, x19, #0x8 >> c: d343fc02 lsr x2, x0, #3 >> * 10: 38e16841 ldrsb w1, [x2, x1] <-- trapping instruction > > This looks to be caused by: > > commit 1b151e2435fc3a9b10c8946c6aebe9f3e1938c55 > Author: Matthew Wilcox (Oracle) > Date: Mon Aug 14 15:41:00 2023 +0100 > > block: Remove special-casing of compound pages I suspect this should fix it. diff --git a/block/bio.c b/block/bio.c index b9642a41f286..d271f093abb9 100644 --- a/block/bio.c +++ b/block/bio.c @@ -1150,6 +1150,12 @@ void __bio_release_pages(struct bio *bio, bool mark_dirty) { struct folio_iter fi; + /* + * No pages, nothing to do + */ + if (!bio->bi_vcnt) + return; + bio_for_each_folio_all(fi, bio) { struct page *page; size_t done = 0; -- Jens Axboe