[syzbot] [wireless?] UBSAN: shift-out-of-bounds in ieee80211_parse_tx_radiotap

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3e48a11675c5 Merge tag 'f2fs-for-7.0-rc1' of git://git.ker..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=126256e6580000
kernel config: https://syzkaller.appspot.com/x/.config?x=bdcbd6339981e22b
dashboard link: https://syzkaller.appspot.com/bug?extid=8e0622f6d9446420271f
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15fd6c02580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1026fe5a580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-3e48a116.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0749cae3d374/vmlinux-3e48a116.xz
kernel image: https://storage.googleapis.com/syzbot-assets/425b8d5bc900/bzImage-3e48a116.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8e0622...@syzkaller.appspotmail.com

------------[ cut here ]------------
UBSAN: shift-out-of-bounds in net/mac80211/tx.c:2174:30
shift exponent 235 is too large for 64-bit type 'unsigned long'
CPU: 0 UID: 0 PID: 5454 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
ubsan_epilogue+0xa/0x30 lib/ubsan.c:233
__ubsan_handle_shift_out_of_bounds+0x385/0x410 lib/ubsan.c:494
ieee80211_parse_tx_radiotap+0xadb/0x1950 net/mac80211/tx.c:2174
ieee80211_monitor_start_xmit+0xb1f/0x1250 net/mac80211/tx.c:2451
__netdev_start_xmit include/linux/netdevice.h:5275 [inline]
netdev_start_xmit include/linux/netdevice.h:5284 [inline]
xmit_one net/core/dev.c:3864 [inline]
dev_hard_start_xmit+0x2d8/0x870 net/core/dev.c:3880
__dev_queue_xmit+0x168f/0x38a0 net/core/dev.c:4829
packet_snd net/packet/af_packet.c:3077 [inline]
packet_sendmsg+0x3eb6/0x50f0 net/packet/af_packet.c:3109
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg net/socket.c:742 [inline]
__sys_sendto+0x709/0x7a0 net/socket.c:2206
__do_sys_sendto net/socket.c:2213 [inline]
__se_sys_sendto net/socket.c:2209 [inline]
__x64_sys_sendto+0xde/0x100 net/socket.c:2209
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f251db9bf79
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 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 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff388b1f78 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f251de15fa0 RCX: 00007f251db9bf79
RDX: 0000000000000038 RSI: 0000200000000640 RDI: 0000000000000007
RBP: 00007f251dc327e0 R08: 0000200000000380 R09: 0000000000000014
R10: 0000000004000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f251de15fac R14: 00007f251de15fa0 R15: 00007f251de15fa0
</TASK>
---[ end trace ]---


---
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[syzbot]

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***

Subject: [PATCH] wifi: mac80211: limit injected antenna index in ieee80211_parse_tx_radiotap
Author: karti...@gmail.com

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master


When parsing the radiotap header of an injected frame,
ieee80211_parse_tx_radiotap() uses the IEEE80211_RADIOTAP_ANTENNA value
directly as a shift count:

info->control.antennas |= BIT(*iterator.this_arg);

*iterator.this_arg is an 8-bit value taken straight from the frame
supplied by userspace, so BIT() can be asked to shift by up to 255. That
is undefined behaviour on the unsigned long and is reported by UBSAN:

UBSAN: shift-out-of-bounds in net/mac80211/tx.c:2174:30
shift exponent 235 is too large for 64-bit type 'unsigned long'

Call Trace:

ieee80211_parse_tx_radiotap+0xadb/0x1950 net/mac80211/tx.c:2174
ieee80211_monitor_start_xmit+0xb1f/0x1250 net/mac80211/tx.c:2451

...
packet_sendmsg+0x3eb6/0x50f0 net/packet/af_packet.c:3109

info->control.antennas is a 2-bit bitmap (u8 antennas:2), so only antenna
indices 0 and 1 can ever be represented. Ignore any larger value instead
of shifting out of bounds.

Reported-by: syzbot+8e0622...@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=8e0622f6d9446420271f
Fixes: ef246a1480cc ("wifi: mac80211: support antenna control in injection")
Signed-off-by: Deepanshu Kartikey <karti...@gmail.com>
---
net/mac80211/tx.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index b487d2330f25..ea7f63e1fc17 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -2181,7 +2181,9 @@ bool ieee80211_parse_tx_radiotap(struct sk_buff *skb,

case IEEE80211_RADIOTAP_ANTENNA:
/* this can appear multiple times, keep a bitmap */
- info->control.antennas |= BIT(*iterator.this_arg);
+ /* control.antennas is only a 2-bit bitmap */
+ if (*iterator.this_arg < 2)
+ info->control.antennas |= BIT(*iterator.this_arg);
break;

case IEEE80211_RADIOTAP_DATA_RETRIES:
--
2.43.0

[syzbot]

Hello,

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

failed to copy syz-execprog to VM: scp failed: failed to run ["scp" "-P" "32991" "-F" "/dev/null" "-o" "UserKnownHostsFile=/dev/null" "-o" "IdentitiesOnly=yes" "-o" "BatchMode=yes" "-o" "StrictHostKeyChecking=no" "-o" "ConnectTimeout=10" "-v" "-O" "/syzkaller/jobs/linux/gopath/src/github.com/google/syzkaller/bin/linux_amd64/syz-execprog" "root@localhost:/syz-execprog"]: exit status 1



syzkaller build log:
go env (err=<nil>)
AR='ar'
CC='gcc'
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_ENABLED='1'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
CXX='g++'
GCCGO='gccgo'
GO111MODULE='auto'
GOAMD64='v1'
GOARCH='amd64'
GOAUTH='netrc'
GOBIN=''
GOCACHE='/syzkaller/.cache/go-build'
GOCACHEPROG=''
GODEBUG=''
GOENV='/syzkaller/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFIPS140='off'
GOFLAGS=''
GOGCCFLAGS='-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build2514959048=/tmp/go-build -gno-record-gcc-switches'
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMOD='/syzkaller/jobs/linux/gopath/src/github.com/google/syzkaller/go.mod'
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'
GOTELEMETRY='local'
GOTELEMETRYDIR='/syzkaller/.config/go/telemetry'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/usr/local/go/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.26.0'
GOWORK=''
PKG_CONFIG='pkg-config'

git status (err=<nil>)
HEAD detached at 1e62d1982527
nothing to commit, working tree clean


tput: No value for $TERM and no -T specified
tput: No value for $TERM and no -T specified
Makefile:31: run command via tools/syz-env for best compatibility, see:
Makefile:32: https://github.com/google/syzkaller/blob/master/docs/contributing.md#using-syz-env
go list -f '{{.Stale}}' -ldflags="-s -w -X github.com/google/syzkaller/prog.GitRevision=1e62d1982527c3b4e18df04d61f2560fa1f434cc -X github.com/google/syzkaller/prog.gitRevisionDate=20260213-152336" ./sys/syz-sysgen | grep -q false || go install -ldflags="-s -w -X github.com/google/syzkaller/prog.GitRevision=1e62d1982527c3b4e18df04d61f2560fa1f434cc -X github.com/google/syzkaller/prog.gitRevisionDate=20260213-152336" ./sys/syz-sysgen
make .descriptions
tput: No value for $TERM and no -T specified
tput: No value for $TERM and no -T specified
Makefile:31: run command via tools/syz-env for best compatibility, see:
Makefile:32: https://github.com/google/syzkaller/blob/master/docs/contributing.md#using-syz-env
bin/syz-sysgen
touch .descriptions
GOOS=linux GOARCH=amd64 go build -ldflags="-s -w -X github.com/google/syzkaller/prog.GitRevision=1e62d1982527c3b4e18df04d61f2560fa1f434cc -X github.com/google/syzkaller/prog.gitRevisionDate=20260213-152336" -o ./bin/linux_amd64/syz-execprog github.com/google/syzkaller/tools/syz-execprog
mkdir -p ./bin/linux_amd64
g++ -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 -Wno-unused-but-set-variable -Wno-unused-command-line-argument -static-pie -std=c++17 -I. -Iexecutor/_include -DGOOS_linux=1 -DGOARCH_amd64=1 \
-DHOSTGOOS_linux=1 -DGIT_REVISION=\"1e62d1982527c3b4e18df04d61f2560fa1f434cc\"
/usr/bin/ld: /tmp/ccX0T21K.o: in function `Connection::Connect(char const*, char const*)':
executor.cc:(.text._ZN10Connection7ConnectEPKcS1_[_ZN10Connection7ConnectEPKcS1_]+0x386): warning: Using 'gethostbyname' in statically linked applications requires at runtime the shared libraries from the glibc version used for linking
./tools/check-syzos.sh 2>/dev/null



Tested on:

commit: 174914ea Merge tag 'v7.1-rc6-smb3-client-fixes' of git..
git tree: upstream
kernel config: https://syzkaller.appspot.com/x/.config?x=78cff8966478b1fd

dashboard link: https://syzkaller.appspot.com/bug?extid=8e0622f6d9446420271f
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

patch: https://syzkaller.appspot.com/x/patch.diff?x=17e3ad2e580000