linux-kernel - Re: [syzbot] [afs?] KASAN: slab-use-after-free Read in afs_dynroot

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Message-ID: <67ea50aa.050a0220.1547ec.0122.GAE@google.com>
Date: Mon, 31 Mar 2025 01:22:02 -0700
From: syzbot <syzbot+1aa62e6852a6ad1c7944@...kaller.appspotmail.com>
To: dhowells@...hat.com, linux-afs@...ts.infradead.org, 
	linux-kernel@...r.kernel.org, marc.dionne@...istor.com, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [afs?] KASAN: slab-use-after-free Read in afs_dynroot_readdir

Hello,

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

0000000 0000000000000031 0000726565666965
ZMM26=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000021 0000000000000000 0000000000000031 00006d5f65636864
ZMM27=0000000000000000 0000000000000000 0000000000000000 0000000000000000 bfbfbfbfbfbfbfbf bfbfbfbfbfbfbfbf bfbfbfbfbfbfbfbf bfbf2b313423342c
ZMM28=0000000000000000 0000000000000000 0000000000000000 0000000000000000 262821df2e2e33df 3228df3232202b22 df312e232d2435bf 2324353124322431
ZMM29=0000000000000000 0000000000000000 0000000000000000 0000000000000000 4141414141414141 4141414141414141 4141414141414141 4141414141414141
ZMM30=0000000000000000 0000000000000000 0000000000000000 0000000000000000 1a1a1a1a1a1a1a1a 1a1a1a1a1a1a1a1a 1a1a1a1a1a1a1a1a 1a1a1a1a1a1a1a1a
ZMM31=0000000000000000 0000000000000000 0000000000000000 0000000000000000 2020202020202020 2020202020202020 2020202020202020 2020202020202020
info registers vcpu 2

CPU#2
RAX=0000000000033bfc RBX=0000000000000002 RCX=ffffffff8b6b32d9 RDX=ffffed100d4c65be
RSI=ffffffff8bf428a0 RDI=ffffffff81918dd1 RBP=ffffed1003ad1910 RSP=ffffc90000187e00
R8 =0000000000000000 R9 =ffffed100d4c65bd R10=ffff88806a632deb R11=ffffffff9acc36a8
R12=0000000000000002 R13=ffff88801d68c880 R14=ffffffff90847210 R15=0000000000000000
RIP=ffffffff8b6b46cf RFL=00000246 [---Z-P-] CPL=0 II=0 A20=1 SMM=0 HLT=1
ES =0000 0000000000000000 ffffffff 00c00000
CS =0010 0000000000000000 ffffffff 00a09b00 DPL=0 CS64 [-RA]
SS =0018 0000000000000000 ffffffff 00c09300 DPL=0 DS   [-WA]
DS =0000 0000000000000000 ffffffff 00c00000
FS =0000 0000000000000000 ffffffff 00c00000
GS =0000 ffff8880d6bfa000 ffffffff 00c00000
LDT=0000 0000000000000000 ffffffff 00c00000
TR =0040 fffffe0000091000 00004087 00008b00 DPL=0 TSS64-busy
GDT=     fffffe000008f000 0000007f
IDT=     fffffe0000000000 00000fff
CR0=80050033 CR2=00007ffe3a3f24b8 CR3=000000000e182000 CR4=00352ef0
DR0=0000000000000000 DR1=0000000000000000 DR2=0000000000000000 DR3=0000000000000000 
DR6=00000000fffe0ff0 DR7=0000000000000400
EFER=0000000000000d01
FCW=037f FSW=0000 [ST=0] FTW=00 MXCSR=00001f80
FPR0=0000000000000000 0000 FPR1=0000000000000000 0000
FPR2=0000000000000000 0000 FPR3=0000000000000000 0000
FPR4=0000000000000000 0000 FPR5=0000000000000000 0000
FPR6=0000000000000000 0000 FPR7=0000000000000000 0000
Opmask00=0000000000062003 Opmask01=00000000001000c0 Opmask02=000000000fffffff Opmask03=0000000000000000
Opmask04=0000000000000000 Opmask05=0000000000000000 Opmask06=0000000000000000 Opmask07=0000000000000000
ZMM00=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000034687465
ZMM01=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 00007ffe3a3e2280 0000003000000008
ZMM02=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 2e2e2e2e2e2e2e2e 2e2e2e2e2e2e2e2e
ZMM03=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 000000ff00000000
ZMM04=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000
ZMM05=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 ffff0000ff000000 0000000000000000
ZMM06=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000
ZMM07=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000
ZMM08=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000
ZMM09=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000
ZMM10=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000
ZMM11=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000
ZMM12=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000
ZMM13=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000
ZMM14=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000
ZMM15=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000
ZMM16=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000
ZMM17=0000000000000000 0000000000000000 0000000000000000 0000000000000000 2525252525252525 2525252525252525 2525252525252525 2525252525252525
ZMM18=0000000000000000 0000000000000000 0000000000000000 0000000000000000 50422064656e7761 7073203a73250050 5241006e65706f5f 667062203a732500
ZMM19=0000000000000000 0000000000000000 0000000000000000 0000000000000000 50420541404b5244 5556051f56000050 5241004b40554a5f 435547051f560000
ZMM20=0000000000000000 0000000000000000 0000000000000000 0000000000000000 00005644101183e0 00005644101197e0 0000000000000181 0000000000000000
ZMM21=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000041 0700000000000029 00316e6170772f74 656e2f317968702f
ZMM22=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000021 0000000000000000 0000564475764233 73656d5f70636864
ZMM23=0000000000000000 0000000000000000 0000000000000000 0000000000000000 725f0f7b5f6fd661 72610f657b69f37f 6567777777777fff 7f7f7d7f75777965
ZMM24=0000000000000000 0000000000000000 0000000000000000 0000000000000000 7865686e69622000 7761722000696963 73612000656d616e 6420006e69616d6f
ZMM25=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000021 0000000000000000 0000000000000031 0000726565666965
ZMM26=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000021 0000000000000000 0000000000000031 00006d5f65636864
ZMM27=0000000000000000 0000000000000000 0000000000000000 0000000000000000 bfbfbfbfbfbfbfbf bfbfbfbfbfbfbfbf bfbfbfbfbfbfbfbf bfbf2b313423342c
ZMM28=0000000000000000 0000000000000000 0000000000000000 0000000000000000 262821df2e2e33df 3228df3232202b22 df312e232d2435bf 2324353124322431
ZMM29=0000000000000000 0000000000000000 0000000000000000 0000000000000000 4141414141414141 4141414141414141 4141414141414141 4141414141414141
ZMM30=0000000000000000 0000000000000000 0000000000000000 0000000000000000 1a1a1a1a1a1a1a1a 1a1a1a1a1a1a1a1a 1a1a1a1a1a1a1a1a 1a1a1a1a1a1a1a1a
ZMM31=0000000000000000 0000000000000000 0000000000000000 0000000000000000 2020202020202020 2020202020202020 2020202020202020 2020202020202020
info registers vcpu 3

CPU#3
RAX=00000000000275d4 RBX=0000000000000003 RCX=ffffffff8b6b32d9 RDX=ffffed100d4e65be
RSI=ffffffff8bf428a0 RDI=ffffffff81918dd1 RBP=ffffed1003b54000 RSP=ffffc90000197e00
R8 =0000000000000000 R9 =ffffed100d4e65bd R10=ffff88806a732deb R11=ffffffff9ada5038
R12=0000000000000003 R13=ffff88801daa0000 R14=ffffffff90847210 R15=0000000000000000
RIP=ffffffff8b6b46cf RFL=00000246 [---Z-P-] CPL=0 II=0 A20=1 SMM=0 HLT=1
ES =0000 0000000000000000 ffffffff 00c00000
CS =0010 0000000000000000 ffffffff 00a09b00 DPL=0 CS64 [-RA]
SS =0018 0000000000000000 ffffffff 00c09300 DPL=0 DS   [-WA]
DS =0000 0000000000000000 ffffffff 00c00000
FS =0000 0000000000000000 ffffffff 00c00000
GS =0000 ffff8880d6cfa000 ffffffff 00c00000
LDT=0000 0000000000000000 ffffffff 00c00000
TR =0040 fffffe00000d8000 00004087 00008b00 DPL=0 TSS64-busy
GDT=     fffffe00000d6000 0000007f
IDT=     fffffe0000000000 00000fff
CR0=80050033 CR2=00005643d1f0e680 CR3=0000000028726000 CR4=00352ef0
DR0=0000000000000000 DR1=0000000000000000 DR2=0000000000000000 DR3=0000000000000000 
DR6=00000000fffe0ff0 DR7=0000000000000400
EFER=0000000000000d01
FCW=037f FSW=0000 [ST=0] FTW=00 MXCSR=00001f80
FPR0=0000000000000000 0000 FPR1=0000000000000000 0000
FPR2=0000000000000000 0000 FPR3=0000000000000000 0000
FPR4=0000000000000000 0000 FPR5=0000000000000000 0000
FPR6=0000000000000000 0000 FPR7=0000000000000000 0000
Opmask00=0000000060000000 Opmask01=00000000ffffffff Opmask02=00000000fff80800 Opmask03=0000000000000000
Opmask04=0000000000000000 Opmask05=0000000000000000 Opmask06=0000000000000000 Opmask07=0000000000000000
ZMM00=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000001
ZMM01=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 00007ffdf1a6b290 0000003000000010
ZMM02=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 6c5f5f0045544156 4952505f4342494c
ZMM03=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 000000000042494c
ZMM04=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 6362696c5f5f0045 5441564952505f43
ZMM05=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000
ZMM06=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000
ZMM07=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000
ZMM08=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000
ZMM09=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000
ZMM10=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000
ZMM11=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000
ZMM12=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000
ZMM13=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000
ZMM14=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000
ZMM15=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000
ZMM16=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000
ZMM17=0000000000000000 0000000000000000 0000000000000000 0000000000000000 2525252525252525 2525252525252525 2525252525252525 2525252525252525
ZMM18=0000000000000000 0000000000000000 0000000000000000 0000000000000000 4f6e3a6d5e007325 2e73250064252e73 2500656c6f736e6f 632f7665642f000a
ZMM19=0000000000000000 0000000000000000 0000000000000000 0000000000000000 4f4b1f485e005600 0b56000041000b56 000040494a564b4a 460a5340410a000a
ZMM20=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000
ZMM21=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000
ZMM22=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000
ZMM23=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000
ZMM24=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000
ZMM25=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000
ZMM26=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000
ZMM27=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000
ZMM28=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000
ZMM29=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000
ZMM30=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000
ZMM31=0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000


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='/syzkaller/jobs/linux/gopath/pkg/mod/golang.org/toolchain@...0.1-go1.23.6.linux-amd64'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/syzkaller/jobs/linux/gopath/pkg/mod/golang.org/toolchain@...0.1-go1.23.6.linux-amd64/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.23.6'
GODEBUG=''
GOTELEMETRY='local'
GOTELEMETRYDIR='/syzkaller/.config/go/telemetry'
GCCGO='gccgo'
GOAMD64='v1'
AR='ar'
CC='gcc'
CXX='g++'
CGO_ENABLED='1'
GOMOD='/syzkaller/jobs/linux/gopath/src/github.com/google/syzkaller/go.mod'
GOWORK=''
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
PKG_CONFIG='pkg-config'
GOGCCFLAGS='-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build1472119147=/tmp/go-build -gno-record-gcc-switches'

git status (err=<nil>)
HEAD detached at 89d30d7360
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}}' ./sys/syz-sysgen | grep -q false || go install ./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=89d30d7360d4a366f8fdf00d6ac56cced7a45b0b -X 'github.com/google/syzkaller/prog.gitRevisionDate=20250325-195331'" -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=\"89d30d7360d4a366f8fdf00d6ac56cced7a45b0b\"
/usr/bin/ld: /tmp/cc2CraHQ.o: in function `Connection::Connect(char const*, char const*)':
executor.cc:(.text._ZN10Connection7ConnectEPKcS1_[_ZN10Connection7ConnectEPKcS1_]+0x104): warning: Using 'gethostbyname' in statically linked applications requires at runtime the shared libraries from the glibc version used for linking


Error text is too large and was truncated, full error text is at:
https://syzkaller.appspot.com/x/error.txt?x=14d623e4580000


Tested on:

commit:         4e82c870 Merge tag 'rust-6.15' of git://git.kernel.org..
git tree:       upstream
kernel config:  https://syzkaller.appspot.com/x/.config?x=d1f30123de5ffff
dashboard link: https://syzkaller.appspot.com/bug?extid=1aa62e6852a6ad1c7944
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=122e47b0580000