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SubjectKASAN: use-after-free Read in reiserfs_fill_super
Hi,

We would like to report the following bug which has been found by our
modified version of syzkaller.

======================================================
description: KASAN: use-after-free Read in reiserfs_fill_super
affected file: fs/reiserfs/inode.c
kernel version: 5.19-rc6
kernel commit: 32346491ddf24599decca06190ebca03ff9de7f8
git tree: upstream
kernel config: https://syzkaller.appspot.com/text?tag=KernelConfig&x=cd73026ceaed1402
crash reproducer: attached
======================================================
Crash log:
======================================================
UG: KASAN: use-after-free in init_inode fs/reiserfs/inode.c:1325 [inline]
BUG: KASAN: use-after-free in reiserfs_read_locked_inode+0x1f9c/0x2300
fs/reiserfs/inode.c:1574
Read of size 4 at addr ffff88819f38c000 by task syz-executor.5/13593

CPU: 0 PID: 13593 Comm: syz-executor.5 Tainted: G OE
5.19.0-rc6-g2eae0556bb9d #2
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
1.13.0-1ubuntu1.1 04/01/2014
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:313 [inline]
print_report.cold+0xe5/0x659 mm/kasan/report.c:429
kasan_report+0x8a/0x1b0 mm/kasan/report.c:491
init_inode fs/reiserfs/inode.c:1325 [inline]
reiserfs_read_locked_inode+0x1f9c/0x2300 fs/reiserfs/inode.c:1574
reiserfs_fill_super+0x126c/0x2f10 fs/reiserfs/super.c:2073
mount_bdev+0x34d/0x410 fs/super.c:1367
legacy_get_tree+0x105/0x220 fs/fs_context.c:610
vfs_get_tree+0x89/0x2f0 fs/super.c:1497
do_new_mount fs/namespace.c:3040 [inline]
path_mount+0x1228/0x1cb0 fs/namespace.c:3370
do_mount+0xf3/0x110 fs/namespace.c:3383
__do_sys_mount fs/namespace.c:3591 [inline]
__se_sys_mount fs/namespace.c:3568 [inline]
__x64_sys_mount+0x18f/0x230 fs/namespace.c:3568
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x46/0xb0
RIP: 0033:0x7f4fe2e8fe8e
Code: 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f
84 00 00 00 00 00 90 f3 0f 1e fa 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d
01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f4fe148b9f8 EFLAGS: 00000202 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0000000020000200 RCX: 00007f4fe2e8fe8e
RDX: 0000000020000040 RSI: 0000000020000100 RDI: 00007f4fe148ba50
RBP: 00007f4fe148ba90 R08: 00007f4fe148ba90 R09: 0000000020000040
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000020000040
R13: 0000000020000100 R14: 00007f4fe148ba50 R15: 0000000020011400
</TASK>

The buggy address belongs to the physical page:
page:ffffea00067ce300 refcount:0 mapcount:-128
mapping:0000000000000000 index:0x1 pfn:0x19f38c
flags: 0x17ff00000000000(node=0|zone=2|lastcpupid=0x7ff)
raw: 017ff00000000000 ffffea000610d9c8 ffffea0006897b08 0000000000000000
raw: 0000000000000001 0000000000000000 00000000ffffff7f 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask
0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), pid 2972, tgid 2972
(systemd-udevd), ts 583268397100, free_ts 649857437696
set_page_owner include/linux/page_owner.h:31 [inline]
post_alloc_hook mm/page_alloc.c:2449 [inline]
prep_new_page+0x297/0x330 mm/page_alloc.c:2456
get_page_from_freelist+0x2142/0x3c80 mm/page_alloc.c:4198
__alloc_pages+0x321/0x710 mm/page_alloc.c:5426
__folio_alloc+0x12/0x40 mm/page_alloc.c:5457
vma_alloc_folio+0xf9/0x6e0 mm/mempolicy.c:2233
alloc_page_vma include/linux/gfp.h:634 [inline]
wp_page_copy+0x1f1/0x1d00 mm/memory.c:3104
do_wp_page+0x52c/0x1840 mm/memory.c:3471
handle_pte_fault mm/memory.c:4921 [inline]
__handle_mm_fault+0x2a69/0x3ee0 mm/memory.c:5042
handle_mm_fault+0x322/0xa80 mm/memory.c:5140
do_user_addr_fault+0x489/0x11c0 arch/x86/mm/fault.c:1397
handle_page_fault arch/x86/mm/fault.c:1484 [inline]
exc_page_fault+0x9e/0x180 arch/x86/mm/fault.c:1540
asm_exc_page_fault+0x27/0x30 arch/x86/include/asm/idtentry.h:570
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1371 [inline]
free_pcp_prepare+0x51f/0xd00 mm/page_alloc.c:1421
free_unref_page_prepare mm/page_alloc.c:3343 [inline]
free_unref_page_list+0x15a/0xe90 mm/page_alloc.c:3475
release_pages+0x10ea/0x2590 mm/swap.c:980
tlb_batch_pages_flush mm/mmu_gather.c:58 [inline]
tlb_flush_mmu_free mm/mmu_gather.c:255 [inline]
tlb_flush_mmu+0xef/0x690 mm/mmu_gather.c:262
tlb_finish_mmu+0x93/0x3c0 mm/mmu_gather.c:353
exit_mmap+0x1de/0x4b0 mm/mmap.c:3164
__mmput kernel/fork.c:1196 [inline]
mmput+0x16b/0x430 kernel/fork.c:1217
exit_mm kernel/exit.c:511 [inline]
do_exit+0xa33/0x2dd0 kernel/exit.c:784
do_group_exit+0xd2/0x2f0 kernel/exit.c:927
__do_sys_exit_group kernel/exit.c:938 [inline]
__se_sys_exit_group kernel/exit.c:936 [inline]
__x64_sys_exit_group+0x3a/0x50 kernel/exit.c:936
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x46/0xb0

Memory state around the buggy address:
ffff88819f38bf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff88819f38bf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88819f38c000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
^
ffff88819f38c080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff88819f38c100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================

--
Thanks and Regards,

Dipanjan
[unhandled content-type:application/octet-stream]// autogenerated by syzkaller (https://github.com/google/syzkaller)

#define _GNU_SOURCE

#include <dirent.h>
#include <endian.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/mount.h>
#include <sys/prctl.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>

#include <linux/loop.h>

#ifndef __NR_memfd_create
#define __NR_memfd_create 319
#endif

static unsigned long long procid;

static void sleep_ms(uint64_t ms)
{
usleep(ms * 1000);
}

static uint64_t current_time_ms(void)
{
struct timespec ts;
if (clock_gettime(CLOCK_MONOTONIC, &ts))
exit(1);
return (uint64_t)ts.tv_sec * 1000 + (uint64_t)ts.tv_nsec / 1000000;
}

static bool write_file(const char* file, const char* what, ...)
{
char buf[1024];
va_list args;
va_start(args, what);
vsnprintf(buf, sizeof(buf), what, args);
va_end(args);
buf[sizeof(buf) - 1] = 0;
int len = strlen(buf);
int fd = open(file, O_WRONLY | O_CLOEXEC);
if (fd == -1)
return false;
if (write(fd, buf, len) != len) {
int err = errno;
close(fd);
errno = err;
return false;
}
close(fd);
return true;
}

struct fs_image_segment {
void* data;
uintptr_t size;
uintptr_t offset;
};

#define IMAGE_MAX_SEGMENTS 4096
#define IMAGE_MAX_SIZE (129 << 20)

static unsigned long fs_image_segment_check(unsigned long size, unsigned long nsegs, struct fs_image_segment* segs)
{
if (nsegs > IMAGE_MAX_SEGMENTS)
nsegs = IMAGE_MAX_SEGMENTS;
for (size_t i = 0; i < nsegs; i++) {
if (segs[i].size > IMAGE_MAX_SIZE)
segs[i].size = IMAGE_MAX_SIZE;
segs[i].offset %= IMAGE_MAX_SIZE;
if (segs[i].offset > IMAGE_MAX_SIZE - segs[i].size)
segs[i].offset = IMAGE_MAX_SIZE - segs[i].size;
if (size < segs[i].offset + segs[i].offset)
size = segs[i].offset + segs[i].offset;
}
if (size > IMAGE_MAX_SIZE)
size = IMAGE_MAX_SIZE;
return size;
}
static int setup_loop_device(long unsigned size, long unsigned nsegs, struct fs_image_segment* segs, const char* loopname, int* memfd_p, int* loopfd_p)
{
int err = 0, loopfd = -1;
size = fs_image_segment_check(size, nsegs, segs);
int memfd = syscall(__NR_memfd_create, "syzkaller", 0);
if (memfd == -1) {
err = errno;
goto error;
}
if (ftruncate(memfd, size)) {
err = errno;
goto error_close_memfd;
}
for (size_t i = 0; i < nsegs; i++) {
if (pwrite(memfd, segs[i].data, segs[i].size, segs[i].offset) < 0) {
}
}
loopfd = open(loopname, O_RDWR);
if (loopfd == -1) {
err = errno;
goto error_close_memfd;
}
if (ioctl(loopfd, LOOP_SET_FD, memfd)) {
if (errno != EBUSY) {
err = errno;
goto error_close_loop;
}
ioctl(loopfd, LOOP_CLR_FD, 0);
usleep(1000);
if (ioctl(loopfd, LOOP_SET_FD, memfd)) {
err = errno;
goto error_close_loop;
}
}
*memfd_p = memfd;
*loopfd_p = loopfd;
return 0;

error_close_loop:
close(loopfd);
error_close_memfd:
close(memfd);
error:
errno = err;
return -1;
}

static long syz_mount_image(volatile long fsarg, volatile long dir, volatile unsigned long size, volatile unsigned long nsegs, volatile long segments, volatile long flags, volatile long optsarg)
{
struct fs_image_segment* segs = (struct fs_image_segment*)segments;
int res = -1, err = 0, loopfd = -1, memfd = -1, need_loop_device = !!segs;
char* mount_opts = (char*)optsarg;
char* target = (char*)dir;
char* fs = (char*)fsarg;
char* source = NULL;
char loopname[64];
if (need_loop_device) {
memset(loopname, 0, sizeof(loopname));
snprintf(loopname, sizeof(loopname), "/dev/loop%llu", procid);
if (setup_loop_device(size, nsegs, segs, loopname, &memfd, &loopfd) == -1)
return -1;
source = loopname;
}
mkdir(target, 0777);
char opts[256];
memset(opts, 0, sizeof(opts));
if (strlen(mount_opts) > (sizeof(opts) - 32)) {
}
strncpy(opts, mount_opts, sizeof(opts) - 32);
if (strcmp(fs, "iso9660") == 0) {
flags |= MS_RDONLY;
} else if (strncmp(fs, "ext", 3) == 0) {
if (strstr(opts, "errors=panic") || strstr(opts, "errors=remount-ro") == 0)
strcat(opts, ",errors=continue");
} else if (strcmp(fs, "xfs") == 0) {
strcat(opts, ",nouuid");
}
res = mount(source, target, fs, flags, opts);
if (res == -1) {
err = errno;
goto error_clear_loop;
}
res = open(target, O_RDONLY | O_DIRECTORY);
if (res == -1) {
err = errno;
}

error_clear_loop:
if (need_loop_device) {
ioctl(loopfd, LOOP_CLR_FD, 0);
close(loopfd);
close(memfd);
}
errno = err;
return res;
}

static void kill_and_wait(int pid, int* status)
{
kill(-pid, SIGKILL);
kill(pid, SIGKILL);
for (int i = 0; i < 100; i++) {
if (waitpid(-1, status, WNOHANG | __WALL) == pid)
return;
usleep(1000);
}
DIR* dir = opendir("/sys/fs/fuse/connections");
if (dir) {
for (;;) {
struct dirent* ent = readdir(dir);
if (!ent)
break;
if (strcmp(ent->d_name, ".") == 0 || strcmp(ent->d_name, "..") == 0)
continue;
char abort[300];
snprintf(abort, sizeof(abort), "/sys/fs/fuse/connections/%s/abort", ent->d_name);
int fd = open(abort, O_WRONLY);
if (fd == -1) {
continue;
}
if (write(fd, abort, 1) < 0) {
}
close(fd);
}
closedir(dir);
} else {
}
while (waitpid(-1, status, __WALL) != pid) {
}
}

static void reset_loop()
{
char buf[64];
snprintf(buf, sizeof(buf), "/dev/loop%llu", procid);
int loopfd = open(buf, O_RDWR);
if (loopfd != -1) {
ioctl(loopfd, LOOP_CLR_FD, 0);
close(loopfd);
}
}

static void setup_test()
{
prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
setpgrp();
write_file("/proc/self/oom_score_adj", "1000");
}

static void execute_one(void);

#define WAIT_FLAGS __WALL

static void loop(void)
{
int iter = 0;
for (;; iter++) {
reset_loop();
int pid = fork();
if (pid < 0)
exit(1);
if (pid == 0) {
setup_test();
execute_one();
exit(0);
}
int status = 0;
uint64_t start = current_time_ms();
for (;;) {
if (waitpid(-1, &status, WNOHANG | WAIT_FLAGS) == pid)
break;
sleep_ms(1);
if (current_time_ms() - start < 5000)
continue;
kill_and_wait(pid, &status);
break;
}
}
}

void execute_one(void)
{
memcpy((void*)0x20000040, "reiserfs\000", 9);
memcpy((void*)0x20000100, "./file0\000", 8);
*(uint64_t*)0x20000200 = 0x20010000;
memcpy((void*)0x20010000, "\x00\x40\x00\x00\x68\x02\x00\x00\x97\x3d\x00\x00\x12\x00\x00\x00\x00\x00\x00\x00\x84\x3d\x00\x00\x00\x01\x00\x00\x61\x1c\xad\x49\xe1\x00\x00\x00\x1e\x00\x00\x00\x00\x00\x00\x00\x00\x10\xec\x03\x02\x00\x01\x00\x52\x65\x49\x73\x45\x72\x33\x46\x73\x00\x00\x00\x02\x00\x00\x00\x02", 69);
*(uint64_t*)0x20000208 = 0x45;
*(uint64_t*)0x20000210 = 0x10000;
*(uint64_t*)0x20000218 = 0x20011100;
memcpy((void*)0x20011100, "\x80\x00\x00\x03\x00\x20\x00\x00\x00\x00\x00\x00\x12\x00\x00\x00\x00\x00\x00\x00\x84\x3d\x00\x00\x00\x01\x00\x00\x61\x1c\xad\x49\xe1", 33);
*(uint64_t*)0x20000220 = 0x21;
*(uint64_t*)0x20000228 = 0x3d96000;
*(uint64_t*)0x20000230 = 0x20000280;
memcpy((void*)0x20000280, "\x01\x00\x02\x00\x75\x0f\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\x00\x00\x00\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x20\x00\xe0\x0f\x10\x00\x01\x00\x00\x00\x02\x00\x00\x00\x01\x00\x00\x00\xf4\x01\x00\x00\x02\x00\x23\x00\xbd\x0f\xf9\x0b\x71\x85\xf1\x1a\xc8\x09\x10\x8c\x77\x8d\x51\xe3\xe0\x43\xcb\x42\x20\x23\x61\x74\xc7\x8c\x42\xb1\x79\x5b\x37\x3c\xcf\x55\x37\xfa\x6c\x8b\x4c\x1b\xab\xd7\xf1\xcc\xf3\x48\x07\x55\x75\x1b\xc5\x30\xc9\xa7\xfb\x72\x41\xbd\x73\xcc\x02\x82\xae\x33\xdc\x1e\x8d\x35\xe3\xb3\x0f\x5b\xff\xf3\x3e\x0c\x10\xbd\xc3\x34\x11\x6f\xb3\x19\x36\x26\x6d\x74\x93\x69\xef\x5f\x46\x28\x66\x32\xae\xdd\xa8\x68\x21\x79\xd4\xd2\x90\x00\x00\x00\x00\x8d\xbd\x44\xdd\xc4\xa1\xc7\x5a\xb7\x9b\x5b\x94\xd6\x5c\xd1\x95\x88\x55\x40\xd1\xc0\x3d\x68\x40\x23\x2d\xdd\xa8\x3d\xd6\x70\xb6\x37\x78\x74\xd0\xf1\x51\xa2\x1b\x68\x27\x77\x9b\xf7\xb1\x0f\xf8\x60\x7a\x65\x83\x77\xd9\x00\x00\x0c\xcb\xba\xa7\xc5\xe7\x1b\xf2\x1d\x89\xe1\xe2\x46\xec\x1c\x98\x96\x67\x26\x04\x0b\x31\xac\x7f\x54\xc9\x7a\x67\x1b\x53\xf9\x99\x0d\xac\x11\xf0\x79\xbd\xa4\xdb\x57\xc9\x3f\xa1\x01\xd9\xd5\x33\x17\x40\xef\x9b\x9d\x69\xc3\x28\xa0\xea\xdf\x29\xc8\xc6\x3d\xe2\x48\xc7\x95\x93\x28\x15\x0f\x17\xb9\xcf\x72", 308);
*(uint64_t*)0x20000238 = 0x134;
*(uint64_t*)0x20000240 = 0x3d97000;
*(uint8_t*)0x20011400 = 0;
syz_mount_image(0x20000040, 0x20000100, 0, 3, 0x20000200, 0, 0x20011400);

}
int main(void)
{
syscall(__NR_mmap, 0x1ffff000ul, 0x1000ul, 0ul, 0x32ul, -1, 0ul);
syscall(__NR_mmap, 0x20000000ul, 0x1000000ul, 7ul, 0x32ul, -1, 0ul);
syscall(__NR_mmap, 0x21000000ul, 0x1000ul, 0ul, 0x32ul, -1, 0ul);
loop();
return 0;
}
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