Date:   Sat, 22 Oct 2022 19:53:17 -0700
From:   syzbot <syzbot+ef17b5b364116518fd65@...kaller.appspotmail.com>
To:     hdanton@...a.com, linux-kernel@...r.kernel.org,
        syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] KASAN: use-after-free Read in kernfs_add_one

Hello,

syzbot tried to test the proposed patch but the build/boot failed:

che: Netfs 'afs' registered for caching
[   13.500882][    T1] Btrfs loaded, crc32c=crc32c-intel, assert=on, zoned=yes, fsverity=yes
[   13.510556][    T1] Key type big_key registered
[   13.519302][    T1] Key type encrypted registered
[   13.524584][    T1] ima: No TPM chip found, activating TPM-bypass!
[   13.530967][    T1] Loading compiled-in module X.509 certificates
[   13.538472][    T1] Loaded X.509 cert 'Build time autogenerated kernel key: f850c787ad998c396ae089c083b940ff0a9abb77'
[   13.549867][    T1] ima: Allocated hash algorithm: sha256
[   13.555945][    T1] ima: No architecture policies found
[   13.561723][    T1] evm: Initialising EVM extended attributes:
[   13.568162][    T1] evm: security.selinux (disabled)
[   13.573567][    T1] evm: security.SMACK64
[   13.578111][    T1] evm: security.SMACK64EXEC
[   13.582752][    T1] evm: security.SMACK64TRANSMUTE
[   13.588073][    T1] evm: security.SMACK64MMAP
[   13.592999][    T1] evm: security.apparmor (disabled)
[   13.598532][    T1] evm: security.ima
[   13.602464][    T1] evm: security.capability
[   13.607225][    T1] evm: HMAC attrs: 0x1
[   13.699721][    T1] PM:   Magic number: 10:646:713
[   13.705725][    T1] video4linux radio24: hash matches
[   13.716160][    T1] printk: console [netcon0] enabled
[   13.721404][    T1] netconsole: network logging started
[   13.727580][    T1] gtp: GTP module loaded (pdp ctx size 104 bytes)
[   13.737077][    T1] rdma_rxe: loaded
[   13.741304][    T1] cfg80211: Loading compiled-in X.509 certificates for regulatory database
[   13.753006][    T1] cfg80211: Loaded X.509 cert 'sforshee: 00b28ddf47aef9cea7'
[   13.763068][    T1] ALSA device list:
[   13.764341][    T7] platform regulatory.0: Direct firmware load for regulatory.db failed with error -2
[   13.767026][    T1]   #0: Dummy 1
[   13.776574][    T7] platform regulatory.0: Falling back to sysfs fallback for: regulatory.db
[   13.788911][    T1]   #1: Loopback 1
[   13.792729][    T1]   #2: Virtual MIDI Card 1
[   13.800826][    T1] md: Waiting for all devices to be available before autodetect
[   13.808606][    T1] md: If you don't use raid, use raid=noautodetect
[   13.815242][    T1] md: Autodetecting RAID arrays.
[   13.820269][    T1] md: autorun ...
[   13.823994][    T1] md: ... autorun DONE.
[   13.853970][    T1] EXT4-fs (sda1): mounted filesystem with ordered data mode. Opts: (null). Quota mode: none.
[   13.864437][    T1] VFS: Mounted root (ext4 filesystem) readonly on device 8:1.
[   13.886509][    T1] devtmpfs: mounted
[   13.949731][    T1] Freeing unused kernel image (initmem) memory: 3828K
[   13.956753][    T1] Write protecting the kernel read-only data: 167936k
[   13.969087][    T1] Freeing unused kernel image (text/rodata gap) memory: 2012K
[   13.979387][    T1] Freeing unused kernel image (rodata/data gap) memory: 1688K
[   13.992266][    T1] Failed to set sysctl parameter 'max_rcu_stall_to_panic=1': parameter not found
[   14.002382][    T1] Run /sbin/init as init process
[   14.257070][ T2936] mount (2936) used greatest stack depth: 23376 bytes left
[   14.317912][ T2937] EXT4-fs (sda1): re-mounted. Opts: (null). Quota mode: none.
[   14.357277][ T2939] mkdir (2939) used greatest stack depth: 23296 bytes left
mount: mounting selinuxfs on /sys/fs/selinux failed: No such file or directory
mount: mounting mqueue on /dev/mqueue failed: No such file or directory
mount: [   14.406166][ T2940] mount (2940) used greatest stack depth: 21664 bytes left
mounting hugetlbfs on /dev/hugepages failed: No such file or directory
mount: mounting fuse.lxcfs on /var/lib/lxcfs failed: No such file or directory
Starting syslogd: OK
Starting acpid: OK
Starting klogd: OK
Running sysctl: OK
[   14.952768][ T2965] logger (2965) used greatest stack depth: 21264 bytes left
Populating /dev using udev: [   15.122458][ T2969] udevd[2969]: starting version 3.2.10
[   15.431463][ T2970] udevd[2970]: starting eudev-3.2.10
[   15.433624][ T2969] udevd (2969) used greatest stack depth: 19776 bytes left
[   18.456577][ T2979] ================================================================================
[   18.469857][ T2979] UBSAN: null-ptr-deref in ./include/linux/pagemap.h:1088:17
[   18.538074][ T2979] member access within null pointer of type 'struct folio'
[   18.575904][ T2979] CPU: 0 PID: 2979 Comm: udevd Not tainted 5.16.0-rc3-syzkaller-01043-g1a2fb220edca-dirty #0
[   18.586314][ T2979] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/11/2022
[   18.596595][ T2979] Call Trace:
[   18.599900][ T2979]  <TASK>
[   18.602840][ T2979]  dump_stack_lvl+0x1e3/0x2cb
[   18.607653][ T2979]  ? bfq_pos_tree_add_move+0x451/0x451
[   18.613136][ T2979]  ? panic+0x7e3/0x7e3
[   18.617406][ T2979]  ? mpage_readahead+0x6a0/0x6a0
[   18.622367][ T2979]  ubsan_type_mismatch_common+0x280/0x390
[   18.628692][ T2979]  __ubsan_handle_type_mismatch_v1+0x4a/0x60
[   18.634794][ T2979]  mpage_readahead+0x588/0x6a0
[   18.639606][ T2979]  ? dio_await_one+0x250/0x250
[   18.644440][ T2979]  ? blkdev_fallocate+0x330/0x330
[   18.649751][ T2979]  ? put_page+0x90/0x90
[   18.654283][ T2979]  ? __alloc_pages+0x2fd/0x5f0
[   18.659256][ T2979]  ? blk_start_plug_nr_ios+0xaa/0x210
[   18.664788][ T2979]  read_pages+0x162/0x520
[   18.669173][ T2979]  ? page_cache_ra_unbounded+0x840/0x840
[   18.674829][ T2979]  ? filemap_add_folio+0x1ab/0x220
[   18.680150][ T2979]  ? add_to_page_cache_locked+0x90/0x90
[   18.685994][ T2979]  ? folio_alloc+0x47/0x50
[   18.690543][ T2979]  ? filemap_alloc_folio+0x1a9/0x1c0
[   18.696205][ T2979]  page_cache_ra_unbounded+0x6c1/0x840
[   18.701964][ T2979]  ? read_cache_pages_invalidate_pages+0xa0/0xa0
[   18.708384][ T2979]  ? do_page_cache_ra+0xde/0x100
[   18.713352][ T2979]  force_page_cache_ra+0x288/0x2e0
[   18.718608][ T2979]  filemap_read+0x809/0x23d0
[   18.723270][ T2979]  ? find_get_pages_range_tag+0x570/0x570
[   18.729098][ T2979]  ? memset+0x1f/0x40
[   18.733162][ T2979]  ? generic_file_read_iter+0x9e/0x4a0
[   18.739180][ T2979]  ? memset+0x1f/0x40
[   18.743347][ T2979]  ? init_sync_kiocb+0x303/0x4b0
[   18.748408][ T2979]  vfs_read+0x5cd/0x760
[   18.753197][ T2979]  ? kernel_read+0x1f0/0x1f0
[   18.757837][ T2979]  ? __fget_light+0xcc/0x170
[   18.762803][ T2979]  ksys_read+0x19f/0x2d0
[   18.767273][ T2979]  ? vfs_write+0x720/0x720
[   18.771729][ T2979]  ? syscall_enter_from_user_mode+0x2e/0x1c0
[   18.777991][ T2979]  ? lockdep_hardirqs_on+0x95/0x140
[   18.783257][ T2979]  ? syscall_enter_from_user_mode+0x2e/0x1c0
[   18.789379][ T2979]  do_syscall_64+0x44/0xa0
[   18.794342][ T2979]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[   18.800265][ T2979] RIP: 0033:0x7fef837538fe
[   18.804785][ T2979] Code: c0 e9 e6 fe ff ff 50 48 8d 3d 0e c7 09 00 e8 c9 cf 01 00 66 0f 1f 84 00 00 00 00 00 64 8b 04 25 18 00 00 00 85 c0 75 14 0f 05 <48> 3d 00 f0 ff ff 77 5a c3 66 0f 1f 84 00 00 00 00 00 48 83 ec 28
[   18.824787][ T2979] RSP: 002b:00007ffea8972ab8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
[   18.834099][ T2979] RAX: ffffffffffffffda RBX: 000000007fff0000 RCX: 00007fef837538fe
[   18.842179][ T2979] RDX: 0000000000000040 RSI: 000055f64a2af6d8 RDI: 0000000000000009
[   18.850170][ T2979] RBP: 0000000000000040 R08: 000055f64a2af6b0 R09: 00007fef83823a60
[   18.858243][ T2979] R10: 0000000000200000 R11: 0000000000000246 R12: 000055f64a2af6b0
[   18.866500][ T2979] R13: 000055f64a2af6c8 R14: 000055f64a2b6720 R15: 000055f64a2b66d0
[   18.874677][ T2979]  </TASK>
[   19.500327][ T2991] ================================================================================
[   19.661875][ T2991] UBSAN: object-size-mismatch in net/unix/af_unix.c:1094:14
[   19.717755][ T2991] member access within address ffff88801815e6c8 with insufficient space
[   19.779625][ T2991] for an object of type 'struct sockaddr_un'
[   19.844942][ T2991] CPU: 1 PID: 2991 Comm: udevadm Not tainted 5.16.0-rc3-syzkaller-01043-g1a2fb220edca-dirty #0
[   19.855745][ T2991] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/11/2022
[   19.866130][ T2991] Call Trace:
[   19.869498][ T2991]  <TASK>
[   19.872430][ T2991]  dump_stack_lvl+0x1e3/0x2cb
[   19.877100][ T2991]  ? bfq_pos_tree_add_move+0x451/0x451
[   19.882543][ T2991]  ? panic+0x7e3/0x7e3
[   19.886901][ T2991]  ubsan_type_mismatch_common+0x1e6/0x390
[   19.892637][ T2991]  __ubsan_handle_type_mismatch_v1+0x4a/0x60
[   19.898625][ T2991]  unix_autobind+0x13e/0x4d0
[   19.903239][ T2991]  unix_stream_connect+0x622/0xbf0
[   19.908342][ T2991]  ? bpf_lsm_socket_connect+0x5/0x10
[   19.914131][ T2991]  ? security_socket_connect+0x9d/0xb0
[   19.919703][ T2991]  __x64_sys_connect+0x15b/0x1e0
[   19.924797][ T2991]  ? __sys_connect+0x170/0x170
[   19.929592][ T2991]  ? syscall_enter_from_user_mode+0x2e/0x1c0
[   19.935598][ T2991]  ? lockdep_hardirqs_on+0x95/0x140
[   19.941067][ T2991]  ? syscall_enter_from_user_mode+0x2e/0x1c0
[   19.947035][ T2991]  do_syscall_64+0x44/0xa0
[   19.951623][ T2991]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[   19.957618][ T2991] RIP: 0033:0x7f474d116d23
[   19.962241][ T2991] Code: 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 64 8b 04 25 18 00 00 00 85 c0 75 14 b8 2a 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 55 c3 0f 1f 40 00 48 83 ec 18 89 54 24 0c 48
[   19.982635][ T2991] RSP: 002b:00007fffd159a368 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
[   19.991348][ T2991] RAX: ffffffffffffffda RBX: 0000559aa0cda930 RCX: 00007f474d116d23
[   19.999354][ T2991] RDX: 0000000000000013 RSI: 0000559aa0cda948 RDI: 0000000000000003
[   20.007628][ T2991] RBP: 000000000000001e R08: 000000000000001e R09: 0030312e322e332d
[   20.015622][ T2991] R10: 00007fffd159a4b4 R11: 0000000000000246 R12: 00007fffd159a380
[   20.023593][ T2991] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000007
[   20.031578][ T2991]  </TASK>
[   20.613100][ T2979] ================================================================================
[   20.681439][ T2979] Kernel panic - not syncing: panic_on_warn set ...
[   20.688430][ T2979] CPU: 0 PID: 2979 Comm: udevd Not tainted 5.16.0-rc3-syzkaller-01043-g1a2fb220edca-dirty #0
[   20.698597][ T2979] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/11/2022
[   20.708677][ T2979] Call Trace:
[   20.711976][ T2979]  <TASK>
[   20.714926][ T2979]  dump_stack_lvl+0x1e3/0x2cb
[   20.719636][ T2979]  ? bfq_pos_tree_add_move+0x451/0x451
[   20.725127][ T2979]  ? panic+0x7e3/0x7e3
[   20.729236][ T2979]  panic+0x2f1/0x7e3
[   20.733377][ T2979]  ? ubsan_type_mismatch_common+0x2a4/0x390
[   20.739478][ T2979]  ? fb_is_primary_device+0xcc/0xcc
[   20.744706][ T2979]  ? panic+0x7e3/0x7e3
[   20.748985][ T2979]  ? mpage_readahead+0x6a0/0x6a0
[   20.754056][ T2979]  ubsan_type_mismatch_common+0x38c/0x390
[   20.760262][ T2979]  __ubsan_handle_type_mismatch_v1+0x4a/0x60
[   20.766546][ T2979]  mpage_readahead+0x588/0x6a0
[   20.771338][ T2979]  ? dio_await_one+0x250/0x250
[   20.776581][ T2979]  ? blkdev_fallocate+0x330/0x330
[   20.781833][ T2979]  ? put_page+0x90/0x90
[   20.786019][ T2979]  ? __alloc_pages+0x2fd/0x5f0
[   20.790815][ T2979]  ? blk_start_plug_nr_ios+0xaa/0x210
[   20.796385][ T2979]  read_pages+0x162/0x520
[   20.800836][ T2979]  ? page_cache_ra_unbounded+0x840/0x840
[   20.806593][ T2979]  ? filemap_add_folio+0x1ab/0x220
[   20.811913][ T2979]  ? add_to_page_cache_locked+0x90/0x90
[   20.817565][ T2979]  ? folio_alloc+0x47/0x50
[   20.822089][ T2979]  ? filemap_alloc_folio+0x1a9/0x1c0
[   20.827414][ T2979]  page_cache_ra_unbounded+0x6c1/0x840
[   20.833601][ T2979]  ? read_cache_pages_invalidate_pages+0xa0/0xa0
[   20.840089][ T2979]  ? do_page_cache_ra+0xde/0x100
[   20.845127][ T2979]  force_page_cache_ra+0x288/0x2e0
[   20.850354][ T2979]  filemap_read+0x809/0x23d0
[   20.855676][ T2979]  ? find_get_pages_range_tag+0x570/0x570
[   20.861591][ T2979]  ? memset+0x1f/0x40
[   20.865601][ T2979]  ? generic_file_read_iter+0x9e/0x4a0
[   20.871203][ T2979]  ? memset+0x1f/0x40
[   20.875298][ T2979]  ? init_sync_kiocb+0x303/0x4b0
[   20.880251][ T2979]  vfs_read+0x5cd/0x760
[   20.884603][ T2979]  ? kernel_read+0x1f0/0x1f0
[   20.889200][ T2979]  ? __fget_light+0xcc/0x170
[   20.893838][ T2979]  ksys_read+0x19f/0x2d0
[   20.898157][ T2979]  ? vfs_write+0x720/0x720
[   20.902646][ T2979]  ? syscall_enter_from_user_mode+0x2e/0x1c0
[   20.908616][ T2979]  ? lockdep_hardirqs_on+0x95/0x140
[   20.913812][ T2979]  ? syscall_enter_from_user_mode+0x2e/0x1c0
[   20.919831][ T2979]  do_syscall_64+0x44/0xa0
[   20.924431][ T2979]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[   20.930418][ T2979] RIP: 0033:0x7fef837538fe
[   20.934855][ T2979] Code: c0 e9 e6 fe ff ff 50 48 8d 3d 0e c7 09 00 e8 c9 cf 01 00 66 0f 1f 84 00 00 00 00 00 64 8b 04 25 18 00 00 00 85 c0 75 14 0f 05 <48> 3d 00 f0 ff ff 77 5a c3 66 0f 1f 84 00 00 00 00 00 48 83 ec 28
[   20.954802][ T2979] RSP: 002b:00007ffea8972ab8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
[   20.963380][ T2979] RAX: ffffffffffffffda RBX: 000000007fff0000 RCX: 00007fef837538fe
[   20.971639][ T2979] RDX: 0000000000000040 RSI: 000055f64a2af6d8 RDI: 0000000000000009
[   20.979995][ T2979] RBP: 0000000000000040 R08: 000055f64a2af6b0 R09: 00007fef83823a60
[   20.988207][ T2979] R10: 0000000000200000 R11: 0000000000000246 R12: 000055f64a2af6b0
[   20.996338][ T2979] R13: 000055f64a2af6c8 R14: 000055f64a2b6720 R15: 000055f64a2b66d0
[   21.004453][ T2979]  </TASK>
[   21.007945][ T2979] Kernel Offset: disabled
[   21.012860][ T2979] Rebooting in 86400 seconds..


syzkaller build log:
go env (err=<nil>)
GO111MODULE="auto"
GOARCH="amd64"
GOBIN=""
GOCACHE="/syzkaller/.cache/go-build"
GOENV="/syzkaller/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/syzkaller/jobs/linux/gopath/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/syzkaller/jobs/linux/gopath"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="go1.17"
GCCGO="gccgo"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/syzkaller/jobs/linux/gopath/src/github.com/google/syzkaller/go.mod"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build7159890=/tmp/go-build -gno-record-gcc-switches"

git status (err=<nil>)
HEAD detached at 8bcc32a67
nothing to commit, working tree clean


go list -f '{{.Stale}}' ./sys/syz-sysgen | grep -q false || go install ./sys/syz-sysgen
make .descriptions
bin/syz-sysgen
touch .descriptions
GOOS=linux GOARCH=amd64 go build "-ldflags=-s -w -X github.com/google/syzkaller/prog.GitRevision=8bcc32a67bc7180173447e1a78c03dae096b4231 -X 'github.com/google/syzkaller/prog.gitRevisionDate=20220415-122244'" "-tags=syz_target syz_os_linux syz_arch_amd64 " -o ./bin/linux_amd64/syz-fuzzer github.com/google/syzkaller/syz-fuzzer
GOOS=linux GOARCH=amd64 go build "-ldflags=-s -w -X github.com/google/syzkaller/prog.GitRevision=8bcc32a67bc7180173447e1a78c03dae096b4231 -X 'github.com/google/syzkaller/prog.gitRevisionDate=20220415-122244'" "-tags=syz_target syz_os_linux syz_arch_amd64 " -o ./bin/linux_amd64/syz-execprog github.com/google/syzkaller/tools/syz-execprog
GOOS=linux GOARCH=amd64 go build "-ldflags=-s -w -X github.com/google/syzkaller/prog.GitRevision=8bcc32a67bc7180173447e1a78c03dae096b4231 -X 'github.com/google/syzkaller/prog.gitRevisionDate=20220415-122244'" "-tags=syz_target syz_os_linux syz_arch_amd64 " -o ./bin/linux_amd64/syz-stress github.com/google/syzkaller/tools/syz-stress
mkdir -p ./bin/linux_amd64
gcc -o ./bin/linux_amd64/syz-executor executor/executor.cc \
	-m64 -O2 -pthread -Wall -Werror -Wparentheses -Wunused-const-variable -Wframe-larger-than=16384 -Wno-stringop-overflow -Wno-array-bounds -Wno-format-overflow -static-pie -fpermissive -w -DGOOS_linux=1 -DGOARCH_amd64=1 \
	-DHOSTGOOS_linux=1 -DGIT_REVISION=\"8bcc32a67bc7180173447e1a78c03dae096b4231\"


Error text is too large and was truncated, full error text is at:
https://syzkaller.appspot.com/x/error.txt?x=13defd8a880000


Tested on:

commit:         1a2fb220 skbuff: Extract list pointers to silence comp..
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel config:  https://syzkaller.appspot.com/x/.config?x=7f37c0162d15e714
dashboard link: https://syzkaller.appspot.com/bug?extid=ef17b5b364116518fd65
compiler:       Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2
patch:          https://syzkaller.appspot.com/x/patch.diff?x=146ed6ba880000

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