Revision 633593a808980f82d251d0ca89730d8bb8b0220c authored by Eric Dumazet on 10 March 2022, 00:11:45 UTC, committed by Jakub Kicinski on 10 March 2022, 22:46:42 UTC
syzbot reported a kernel infoleak [1] of 4 bytes. After analysis, it turned out r->idiag_expires is not initialized if inet_sctp_diag_fill() calls inet_diag_msg_common_fill() Make sure to clear idiag_timer/idiag_retrans/idiag_expires and let inet_diag_msg_sctpasoc_fill() fill them again if needed. [1] BUG: KMSAN: kernel-infoleak in instrument_copy_to_user include/linux/instrumented.h:121 [inline] BUG: KMSAN: kernel-infoleak in copyout lib/iov_iter.c:154 [inline] BUG: KMSAN: kernel-infoleak in _copy_to_iter+0x6ef/0x25a0 lib/iov_iter.c:668 instrument_copy_to_user include/linux/instrumented.h:121 [inline] copyout lib/iov_iter.c:154 [inline] _copy_to_iter+0x6ef/0x25a0 lib/iov_iter.c:668 copy_to_iter include/linux/uio.h:162 [inline] simple_copy_to_iter+0xf3/0x140 net/core/datagram.c:519 __skb_datagram_iter+0x2d5/0x11b0 net/core/datagram.c:425 skb_copy_datagram_iter+0xdc/0x270 net/core/datagram.c:533 skb_copy_datagram_msg include/linux/skbuff.h:3696 [inline] netlink_recvmsg+0x669/0x1c80 net/netlink/af_netlink.c:1977 sock_recvmsg_nosec net/socket.c:948 [inline] sock_recvmsg net/socket.c:966 [inline] __sys_recvfrom+0x795/0xa10 net/socket.c:2097 __do_sys_recvfrom net/socket.c:2115 [inline] __se_sys_recvfrom net/socket.c:2111 [inline] __x64_sys_recvfrom+0x19d/0x210 net/socket.c:2111 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x54/0xd0 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x44/0xae Uninit was created at: slab_post_alloc_hook mm/slab.h:737 [inline] slab_alloc_node mm/slub.c:3247 [inline] __kmalloc_node_track_caller+0xe0c/0x1510 mm/slub.c:4975 kmalloc_reserve net/core/skbuff.c:354 [inline] __alloc_skb+0x545/0xf90 net/core/skbuff.c:426 alloc_skb include/linux/skbuff.h:1158 [inline] netlink_dump+0x3e5/0x16c0 net/netlink/af_netlink.c:2248 __netlink_dump_start+0xcf8/0xe90 net/netlink/af_netlink.c:2373 netlink_dump_start include/linux/netlink.h:254 [inline] inet_diag_handler_cmd+0x2e7/0x400 net/ipv4/inet_diag.c:1341 sock_diag_rcv_msg+0x24a/0x620 netlink_rcv_skb+0x40c/0x7e0 net/netlink/af_netlink.c:2494 sock_diag_rcv+0x63/0x80 net/core/sock_diag.c:277 netlink_unicast_kernel net/netlink/af_netlink.c:1317 [inline] netlink_unicast+0x1093/0x1360 net/netlink/af_netlink.c:1343 netlink_sendmsg+0x14d9/0x1720 net/netlink/af_netlink.c:1919 sock_sendmsg_nosec net/socket.c:705 [inline] sock_sendmsg net/socket.c:725 [inline] sock_write_iter+0x594/0x690 net/socket.c:1061 do_iter_readv_writev+0xa7f/0xc70 do_iter_write+0x52c/0x1500 fs/read_write.c:851 vfs_writev fs/read_write.c:924 [inline] do_writev+0x645/0xe00 fs/read_write.c:967 __do_sys_writev fs/read_write.c:1040 [inline] __se_sys_writev fs/read_write.c:1037 [inline] __x64_sys_writev+0xe5/0x120 fs/read_write.c:1037 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x54/0xd0 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x44/0xae Bytes 68-71 of 2508 are uninitialized Memory access of size 2508 starts at ffff888114f9b000 Data copied to user address 00007f7fe09ff2e0 CPU: 1 PID: 3478 Comm: syz-executor306 Not tainted 5.17.0-rc4-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Fixes: 8f840e47f190 ("sctp: add the sctp_diag.c file") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: syzbot <syzkaller@googlegroups.com> Cc: Vlad Yasevich <vyasevich@gmail.com> Cc: Neil Horman <nhorman@tuxdriver.com> Cc: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> Reviewed-by: Xin Long <lucien.xin@gmail.com> Link: https://lore.kernel.org/r/20220310001145.297371-1-eric.dumazet@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
1 parent 26183cf
insert-sys-cert.c
/* Write the contents of the <certfile> into kernel symbol system_extra_cert
*
* Copyright (C) IBM Corporation, 2015
*
* Author: Mehmet Kayaalp <mkayaalp@linux.vnet.ibm.com>
*
* This software may be used and distributed according to the terms
* of the GNU General Public License, incorporated herein by reference.
*
* Usage: insert-sys-cert [-s <System.map> -b <vmlinux> -c <certfile>
*/
#define _GNU_SOURCE
#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <limits.h>
#include <stdbool.h>
#include <errno.h>
#include <stdlib.h>
#include <stdarg.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <unistd.h>
#include <elf.h>
#define CERT_SYM "system_extra_cert"
#define USED_SYM "system_extra_cert_used"
#define LSIZE_SYM "system_certificate_list_size"
#define info(format, args...) fprintf(stderr, "INFO: " format, ## args)
#define warn(format, args...) fprintf(stdout, "WARNING: " format, ## args)
#define err(format, args...) fprintf(stderr, "ERROR: " format, ## args)
#if UINTPTR_MAX == 0xffffffff
#define CURRENT_ELFCLASS ELFCLASS32
#define Elf_Ehdr Elf32_Ehdr
#define Elf_Shdr Elf32_Shdr
#define Elf_Sym Elf32_Sym
#else
#define CURRENT_ELFCLASS ELFCLASS64
#define Elf_Ehdr Elf64_Ehdr
#define Elf_Shdr Elf64_Shdr
#define Elf_Sym Elf64_Sym
#endif
static unsigned char endianness(void)
{
uint16_t two_byte = 0x00FF;
uint8_t low_address = *((uint8_t *)&two_byte);
if (low_address == 0)
return ELFDATA2MSB;
else
return ELFDATA2LSB;
}
struct sym {
char *name;
unsigned long address;
unsigned long offset;
void *content;
int size;
};
static unsigned long get_offset_from_address(Elf_Ehdr *hdr, unsigned long addr)
{
Elf_Shdr *x;
unsigned int i, num_sections;
x = (void *)hdr + hdr->e_shoff;
if (hdr->e_shnum == SHN_UNDEF)
num_sections = x[0].sh_size;
else
num_sections = hdr->e_shnum;
for (i = 1; i < num_sections; i++) {
unsigned long start = x[i].sh_addr;
unsigned long end = start + x[i].sh_size;
unsigned long offset = x[i].sh_offset;
if (addr >= start && addr <= end)
return addr - start + offset;
}
return 0;
}
#define LINE_SIZE 100
static void get_symbol_from_map(Elf_Ehdr *hdr, FILE *f, char *name,
struct sym *s)
{
char l[LINE_SIZE];
char *w, *p, *n;
s->size = 0;
s->address = 0;
s->offset = 0;
if (fseek(f, 0, SEEK_SET) != 0) {
perror("File seek failed");
exit(EXIT_FAILURE);
}
while (fgets(l, LINE_SIZE, f)) {
p = strchr(l, '\n');
if (!p) {
err("Missing line ending.\n");
return;
}
n = strstr(l, name);
if (n)
break;
}
if (!n) {
err("Unable to find symbol: %s\n", name);
return;
}
w = strchr(l, ' ');
if (!w)
return;
*w = '\0';
s->address = strtoul(l, NULL, 16);
if (s->address == 0)
return;
s->offset = get_offset_from_address(hdr, s->address);
s->name = name;
s->content = (void *)hdr + s->offset;
}
static Elf_Sym *find_elf_symbol(Elf_Ehdr *hdr, Elf_Shdr *symtab, char *name)
{
Elf_Sym *sym, *symtab_start;
char *strtab, *symname;
unsigned int link;
Elf_Shdr *x;
int i, n;
x = (void *)hdr + hdr->e_shoff;
link = symtab->sh_link;
symtab_start = (void *)hdr + symtab->sh_offset;
n = symtab->sh_size / symtab->sh_entsize;
strtab = (void *)hdr + x[link].sh_offset;
for (i = 0; i < n; i++) {
sym = &symtab_start[i];
symname = strtab + sym->st_name;
if (strcmp(symname, name) == 0)
return sym;
}
err("Unable to find symbol: %s\n", name);
return NULL;
}
static void get_symbol_from_table(Elf_Ehdr *hdr, Elf_Shdr *symtab,
char *name, struct sym *s)
{
Elf_Shdr *sec;
int secndx;
Elf_Sym *elf_sym;
Elf_Shdr *x;
x = (void *)hdr + hdr->e_shoff;
s->size = 0;
s->address = 0;
s->offset = 0;
elf_sym = find_elf_symbol(hdr, symtab, name);
if (!elf_sym)
return;
secndx = elf_sym->st_shndx;
if (!secndx)
return;
sec = &x[secndx];
s->size = elf_sym->st_size;
s->address = elf_sym->st_value;
s->offset = s->address - sec->sh_addr
+ sec->sh_offset;
s->name = name;
s->content = (void *)hdr + s->offset;
}
static Elf_Shdr *get_symbol_table(Elf_Ehdr *hdr)
{
Elf_Shdr *x;
unsigned int i, num_sections;
x = (void *)hdr + hdr->e_shoff;
if (hdr->e_shnum == SHN_UNDEF)
num_sections = x[0].sh_size;
else
num_sections = hdr->e_shnum;
for (i = 1; i < num_sections; i++)
if (x[i].sh_type == SHT_SYMTAB)
return &x[i];
return NULL;
}
static void *map_file(char *file_name, int *size)
{
struct stat st;
void *map;
int fd;
fd = open(file_name, O_RDWR);
if (fd < 0) {
perror(file_name);
return NULL;
}
if (fstat(fd, &st)) {
perror("Could not determine file size");
close(fd);
return NULL;
}
*size = st.st_size;
map = mmap(NULL, *size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
if (map == MAP_FAILED) {
perror("Mapping to memory failed");
close(fd);
return NULL;
}
close(fd);
return map;
}
static char *read_file(char *file_name, int *size)
{
struct stat st;
char *buf;
int fd;
fd = open(file_name, O_RDONLY);
if (fd < 0) {
perror(file_name);
return NULL;
}
if (fstat(fd, &st)) {
perror("Could not determine file size");
close(fd);
return NULL;
}
*size = st.st_size;
buf = malloc(*size);
if (!buf) {
perror("Allocating memory failed");
close(fd);
return NULL;
}
if (read(fd, buf, *size) != *size) {
perror("File read failed");
close(fd);
return NULL;
}
close(fd);
return buf;
}
static void print_sym(Elf_Ehdr *hdr, struct sym *s)
{
info("sym: %s\n", s->name);
info("addr: 0x%lx\n", s->address);
info("size: %d\n", s->size);
info("offset: 0x%lx\n", (unsigned long)s->offset);
}
static void print_usage(char *e)
{
printf("Usage %s [-s <System.map>] -b <vmlinux> -c <certfile>\n", e);
}
int main(int argc, char **argv)
{
char *system_map_file = NULL;
char *vmlinux_file = NULL;
char *cert_file = NULL;
int vmlinux_size;
int cert_size;
Elf_Ehdr *hdr;
char *cert;
FILE *system_map;
unsigned long *lsize;
int *used;
int opt;
Elf_Shdr *symtab = NULL;
struct sym cert_sym, lsize_sym, used_sym;
while ((opt = getopt(argc, argv, "b:c:s:")) != -1) {
switch (opt) {
case 's':
system_map_file = optarg;
break;
case 'b':
vmlinux_file = optarg;
break;
case 'c':
cert_file = optarg;
break;
default:
break;
}
}
if (!vmlinux_file || !cert_file) {
print_usage(argv[0]);
exit(EXIT_FAILURE);
}
cert = read_file(cert_file, &cert_size);
if (!cert)
exit(EXIT_FAILURE);
hdr = map_file(vmlinux_file, &vmlinux_size);
if (!hdr)
exit(EXIT_FAILURE);
if (vmlinux_size < sizeof(*hdr)) {
err("Invalid ELF file.\n");
exit(EXIT_FAILURE);
}
if ((hdr->e_ident[EI_MAG0] != ELFMAG0) ||
(hdr->e_ident[EI_MAG1] != ELFMAG1) ||
(hdr->e_ident[EI_MAG2] != ELFMAG2) ||
(hdr->e_ident[EI_MAG3] != ELFMAG3)) {
err("Invalid ELF magic.\n");
exit(EXIT_FAILURE);
}
if (hdr->e_ident[EI_CLASS] != CURRENT_ELFCLASS) {
err("ELF class mismatch.\n");
exit(EXIT_FAILURE);
}
if (hdr->e_ident[EI_DATA] != endianness()) {
err("ELF endian mismatch.\n");
exit(EXIT_FAILURE);
}
if (hdr->e_shoff > vmlinux_size) {
err("Could not find section header.\n");
exit(EXIT_FAILURE);
}
symtab = get_symbol_table(hdr);
if (!symtab) {
warn("Could not find the symbol table.\n");
if (!system_map_file) {
err("Please provide a System.map file.\n");
print_usage(argv[0]);
exit(EXIT_FAILURE);
}
system_map = fopen(system_map_file, "r");
if (!system_map) {
perror(system_map_file);
exit(EXIT_FAILURE);
}
get_symbol_from_map(hdr, system_map, CERT_SYM, &cert_sym);
get_symbol_from_map(hdr, system_map, USED_SYM, &used_sym);
get_symbol_from_map(hdr, system_map, LSIZE_SYM, &lsize_sym);
cert_sym.size = used_sym.address - cert_sym.address;
} else {
info("Symbol table found.\n");
if (system_map_file)
warn("System.map is ignored.\n");
get_symbol_from_table(hdr, symtab, CERT_SYM, &cert_sym);
get_symbol_from_table(hdr, symtab, USED_SYM, &used_sym);
get_symbol_from_table(hdr, symtab, LSIZE_SYM, &lsize_sym);
}
if (!cert_sym.offset || !lsize_sym.offset || !used_sym.offset)
exit(EXIT_FAILURE);
print_sym(hdr, &cert_sym);
print_sym(hdr, &used_sym);
print_sym(hdr, &lsize_sym);
lsize = (unsigned long *)lsize_sym.content;
used = (int *)used_sym.content;
if (cert_sym.size < cert_size) {
err("Certificate is larger than the reserved area!\n");
exit(EXIT_FAILURE);
}
/* If the existing cert is the same, don't overwrite */
if (cert_size == *used &&
strncmp(cert_sym.content, cert, cert_size) == 0) {
warn("Certificate was already inserted.\n");
exit(EXIT_SUCCESS);
}
if (*used > 0)
warn("Replacing previously inserted certificate.\n");
memcpy(cert_sym.content, cert, cert_size);
if (cert_size < cert_sym.size)
memset(cert_sym.content + cert_size,
0, cert_sym.size - cert_size);
*lsize = *lsize + cert_size - *used;
*used = cert_size;
info("Inserted the contents of %s into %lx.\n", cert_file,
cert_sym.address);
info("Used %d bytes out of %d bytes reserved.\n", *used,
cert_sym.size);
exit(EXIT_SUCCESS);
}
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