Hi Andrii Nakryiko, Greetings! I used Syzkaller and found that there is BUG: unable to handle kernel paging request in build_id_parse_nofault After bisection and the first bad commit is: " 45b8fc309654 lib/buildid: rename build_id_parse() into build_id_parse_nofault() " All detailed into can be found at: https://github.com/laifryiee/syzkaller_logs/tree/main/241012_225717_build_id_parse_nofault Syzkaller repro code: https://github.com/laifryiee/syzkaller_logs/tree/main/241012_225717_build_id_parse_nofault/repro.c Syzkaller repro syscall steps: https://github.com/laifryiee/syzkaller_logs/tree/main/241012_225717_build_id_parse_nofault/repro.prog Syzkaller report: https://github.com/laifryiee/syzkaller_logs/tree/main/241012_225717_build_id_parse_nofault/repro.report Kconfig(make olddefconfig): https://github.com/laifryiee/syzkaller_logs/tree/main/241012_225717_build_id_parse_nofault/kconfig_origin Bisect info: https://github.com/laifryiee/syzkaller_logs/tree/main/241012_225717_build_id_parse_nofault/bisect_info.log bzImage: https://github.com/laifryiee/syzkaller_logs/raw/refs/heads/main/241012_225717_build_id_parse_nofault/bzImage_8cf0b93919e13d1e8d4466eb4080a4c4d9d66d7b Issue dmesg: https://github.com/laifryiee/syzkaller_logs/blob/main/241012_225717_build_id_parse_nofault/8cf0b93919e13d1e8d4466eb4080a4c4d9d66d7b_dmesg.log " [ 26.168603] ? __pfx___build_id_parse.isra.0+0x10/0x10 [ 26.169447] ? __pfx_d_path+0x10/0x10 [ 26.170068] ? __kasan_kmalloc+0x88/0xa0 [ 26.170743] build_id_parse_nofault+0x4d/0x60 [ 26.171473] perf_event_mmap+0xb44/0xd90 [ 26.172134] ? __pfx_perf_event_mmap+0x10/0x10 [ 26.172895] mmap_region+0x4e7/0x29d0 [ 26.173526] ? __pfx_mmap_region+0x10/0x10 [ 26.174210] ? lockdep_hardirqs_on+0x89/0x110 [ 26.174956] ? __kasan_check_read+0x15/0x20 [ 26.175655] ? mark_lock.part.0+0xf3/0x17b0 [ 26.176369] ? __sanitizer_cov_trace_const_cmp8+0x1c/0x30 [ 26.177277] ? arch_get_unmapped_area_topdown+0x3d6/0x710 [ 26.178195] ? rcu_read_unlock+0x3b/0xc0 [ 26.178879] ? __sanitizer_cov_trace_const_cmp4+0x1a/0x20 [ 26.179808] ? __sanitizer_cov_trace_cmp8+0x1c/0x30 [ 26.180634] ? cap_mmap_addr+0x60/0x330 [ 26.181300] ? security_mmap_addr+0x63/0x1b0 [ 26.182029] ? __sanitizer_cov_trace_const_cmp8+0x1c/0x30 [ 26.182930] ? __get_unmapped_area+0x1a9/0x3b0 [ 26.183705] do_mmap+0xd9b/0x11f0 [ 26.184291] ? __pfx_do_mmap+0x10/0x10 [ 26.184938] ? __pfx_down_write_killable+0x10/0x10 [ 26.185758] vm_mmap_pgoff+0x1ea/0x390 [ 26.186413] ? __pfx_vm_mmap_pgoff+0x10/0x10 [ 26.187129] ? __fget_files+0x23c/0x4b0 [ 26.187803] ksys_mmap_pgoff+0x3dc/0x520 [ 26.188490] __x64_sys_mmap+0x139/0x1d0 [ 26.189143] x64_sys_call+0x18c6/0x20d0 [ 26.189805] do_syscall_64+0x6d/0x140 [ 26.190425] entry_SYSCALL_64_after_hwframe+0x76/0x7e [ 26.191238] RIP: 0033:0x7fb10be3ee5d [ 26.191837] Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 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 8b 0d 93 af 1b 00 f7 d8 64 89 01 48 [ 26.194753] RSP: 002b:00007ffe95b14e28 EFLAGS: 00000212 ORIG_RAX: 0000000000000009 [ 26.195976] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fb10be3ee5d [ 26.197126] RDX: 0000000000000001 RSI: 0000000000002000 RDI: 0000000020000000 [ 26.198282] RBP: 00007ffe95b14f50 R08: 0000000000000004 R09: 0000000000000000 [ 26.199471] R10: 0000000000000011 R11: 0000000000000212 R12: 00007ffe95b150a8 [ 26.200606] R13: 0000000000402eb7 R14: 0000000000404e08 R15: 00007fb10c078000 [ 26.201757] </TASK> [ 26.202132] Modules linked in: [ 26.202663] CR2: ffff888010a44000 [ 26.203219] ---[ end trace 0000000000000000 ]--- [ 26.204002] RIP: 0010:memcmp+0x32/0x50 [ 26.204685] Code: 06 48 39 07 75 17 48 83 c7 08 48 83 c6 08 48 83 ea 08 48 83 fa 07 77 e6 48 85 d2 74 20 31 c9 eb 09 48 83 c1 01 48 39 ca 74 0e <0f> b6 04 0f 44 0f b6 04 0e 44 29 c0 74 e9 c3 cc cc cc cc 31 c0 c3 [ 26.207669] RSP: 0018:ffff88801fa675f0 EFLAGS: 00010246 [ 26.208529] RAX: 0000000000000000 RBX: ffff88801fa67728 RCX: 0000000000000000 [ 26.209655] RDX: 0000000000000004 RSI: ffffffff86583240 RDI: ffff888010a44000 [ 26.210801] RBP: ffff88801fa67750 R08: 0000000000000000 R09: fffff94000085220 [ 26.211929] R10: 0000000000000012 R11: 0000000000000001 R12: ffff888010a17c00 [ 26.213053] R13: ffff888010a44000 R14: dffffc0000000000 R15: 0000000000000000 [ 26.214186] FS: 00007fb10c02d800(0000) GS:ffff88806c500000(0000) knlGS:0000000000000000 [ 26.215467] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 26.216393] CR2: ffff888010a44000 CR3: 00000000124e8000 CR4: 0000000000750ef0 [ 26.217533] PKRU: 55555554 [ 26.217989] note: repro[728] exited with irqs disabled " I hope you find it useful. Regards, Yi Lai --- If you don't need the following environment to reproduce the problem or if you already have one reproduced environment, please ignore the following information. How to reproduce: git clone https://gitlab.com/xupengfe/repro_vm_env.git cd repro_vm_env tar -xvf repro_vm_env.tar.gz cd repro_vm_env; ./start3.sh // it needs qemu-system-x86_64 and I used v7.1.0 // start3.sh will load bzImage_2241ab53cbb5cdb08a6b2d4688feb13971058f65 v6.2-rc5 kernel // You could change the bzImage_xxx as you want // Maybe you need to remove line "-drive if=pflash,format=raw,readonly=on,file=./OVMF_CODE.fd \" for different qemu version You could use below command to log in, there is no password for root. ssh -p 10023 root@localhost After login vm(virtual machine) successfully, you could transfer reproduced binary to the vm by below way, and reproduce the problem in vm: gcc -pthread -o repro repro.c scp -P 10023 repro root@localhost:/root/ Get the bzImage for target kernel: Please use target kconfig and copy it to kernel_src/.config make olddefconfig make -jx bzImage //x should equal or less than cpu num your pc has Fill the bzImage file into above start3.sh to load the target kernel in vm. Tips: If you already have qemu-system-x86_64, please ignore below info. If you want to install qemu v7.1.0 version: git clone https://github.com/qemu/qemu.git cd qemu git checkout -f v7.1.0 mkdir build cd build yum install -y ninja-build.x86_64 yum -y install libslirp-devel.x86_64 ../configure --target-list=x86_64-softmmu --enable-kvm --enable-vnc --enable-gtk --enable-sdl --enable-usb-redir --enable-slirp make make install On Thu, Aug 29, 2024 at 10:42:27AM -0700, Andrii Nakryiko wrote: > Make it clear that build_id_parse() assumes that it can take no page > fault by renaming it and current few users to build_id_parse_nofault(). > > Also add build_id_parse() stub which for now falls back to non-sleepable > implementation, but will be changed in subsequent patches to take > advantage of sleepable context. PROCMAP_QUERY ioctl() on > /proc/<pid>/maps file is using build_id_parse() and will automatically > take advantage of more reliable sleepable context implementation. > > Reviewed-by: Eduard Zingerman <eddyz87@xxxxxxxxx> > Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx> > --- > include/linux/buildid.h | 4 ++-- > kernel/bpf/stackmap.c | 2 +- > kernel/events/core.c | 2 +- > lib/buildid.c | 25 ++++++++++++++++++++++--- > 4 files changed, 26 insertions(+), 7 deletions(-) > > diff --git a/include/linux/buildid.h b/include/linux/buildid.h > index 20aa3c2d89f7..014a88c41073 100644 > --- a/include/linux/buildid.h > +++ b/include/linux/buildid.h > @@ -7,8 +7,8 @@ > #define BUILD_ID_SIZE_MAX 20 > > struct vm_area_struct; > -int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id, > - __u32 *size); > +int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id, __u32 *size); > +int build_id_parse_nofault(struct vm_area_struct *vma, unsigned char *build_id, __u32 *size); > int build_id_parse_buf(const void *buf, unsigned char *build_id, u32 buf_size); > > #if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID) || IS_ENABLED(CONFIG_VMCORE_INFO) > diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c > index c99f8e5234ac..770ae8e88016 100644 > --- a/kernel/bpf/stackmap.c > +++ b/kernel/bpf/stackmap.c > @@ -156,7 +156,7 @@ static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs, > goto build_id_valid; > } > vma = find_vma(current->mm, ips[i]); > - if (!vma || build_id_parse(vma, id_offs[i].build_id, NULL)) { > + if (!vma || build_id_parse_nofault(vma, id_offs[i].build_id, NULL)) { > /* per entry fall back to ips */ > id_offs[i].status = BPF_STACK_BUILD_ID_IP; > id_offs[i].ip = ips[i]; > diff --git a/kernel/events/core.c b/kernel/events/core.c > index c973e3c11e03..c78a77f9dce4 100644 > --- a/kernel/events/core.c > +++ b/kernel/events/core.c > @@ -8851,7 +8851,7 @@ static void perf_event_mmap_event(struct perf_mmap_event *mmap_event) > mmap_event->event_id.header.size = sizeof(mmap_event->event_id) + size; > > if (atomic_read(&nr_build_id_events)) > - build_id_parse(vma, mmap_event->build_id, &mmap_event->build_id_size); > + build_id_parse_nofault(vma, mmap_event->build_id, &mmap_event->build_id_size); > > perf_iterate_sb(perf_event_mmap_output, > mmap_event, > diff --git a/lib/buildid.c b/lib/buildid.c > index e8fc4aeb01f2..c1cbd34f3685 100644 > --- a/lib/buildid.c > +++ b/lib/buildid.c > @@ -293,10 +293,12 @@ static int get_build_id_64(struct freader *r, unsigned char *build_id, __u32 *si > * @build_id: buffer to store build id, at least BUILD_ID_SIZE long > * @size: returns actual build id size in case of success > * > - * Return: 0 on success, -EINVAL otherwise > + * Assumes no page fault can be taken, so if relevant portions of ELF file are > + * not already paged in, fetching of build ID fails. > + * > + * Return: 0 on success; negative error, otherwise > */ > -int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id, > - __u32 *size) > +int build_id_parse_nofault(struct vm_area_struct *vma, unsigned char *build_id, __u32 *size) > { > const Elf32_Ehdr *ehdr; > struct freader r; > @@ -335,6 +337,23 @@ int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id, > return ret; > } > > +/* > + * Parse build ID of ELF file mapped to VMA > + * @vma: vma object > + * @build_id: buffer to store build id, at least BUILD_ID_SIZE long > + * @size: returns actual build id size in case of success > + * > + * Assumes faultable context and can cause page faults to bring in file data > + * into page cache. > + * > + * Return: 0 on success; negative error, otherwise > + */ > +int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id, __u32 *size) > +{ > + /* fallback to non-faultable version for now */ > + return build_id_parse_nofault(vma, build_id, size); > +} > + > /** > * build_id_parse_buf - Get build ID from a buffer > * @buf: ELF note section(s) to parse > -- > 2.43.5 >
