Using vsnprintf or its derivatives with %n can have security
vulnerability implications.
Prior to commit fef20d9c1380
("vsprintf: unify the format decoding layer for its 3 users"),
any use of %n was ignored.
Reintroduce this feature and convert the existing uses of %n
to use the return length from vsnprintf or its derivatives.
Signed-off-by: Joe Perches <j...@perches.com>
Acked-by: KOSAKI Motohiro <kosaki.motoh...@jp.fujitsu.com> (proc bits)
cc: Kees Cook <keesc...@chromium.org>
cc: Frederic Weisbecker <fweis...@gmail.com>
---
Not particularly well tested...
fs/proc/consoles.c | 2 +-
fs/proc/nommu.c | 20 ++++++-------
fs/proc/task_mmu.c | 18 +++++------
fs/proc/task_nommu.c | 20 ++++++-------
lib/vsprintf.c | 21 ++++++-------
net/ipv4/fib_trie.c | 30 ++++++++-----------
net/ipv4/ping.c | 19 ++++++------
net/ipv4/tcp_ipv4.c | 84 +++++++++++++++++++++++++---------------------------
net/ipv4/udp.c | 19 ++++++------
net/phonet/socket.c | 32 ++++++++++----------
net/sctp/objcnt.c | 5 ++--
11 files changed, 132 insertions(+), 138 deletions(-)
diff --git a/fs/proc/consoles.c b/fs/proc/consoles.c
index b701eaa..42f2bb7 100644
--- a/fs/proc/consoles.c
+++ b/fs/proc/consoles.c
@@ -47,7 +47,7 @@ static int show_console_dev(struct seq_file *m, void *v)
con_flags[a].name : ' ';
flags[a] = 0;
- seq_printf(m, "%s%d%n", con->name, con->index, &len);
+ len = seq_printf(m, "%s%d", con->name, con->index);
len = 21 - len;
if (len < 1)
len = 1;
diff --git a/fs/proc/nommu.c b/fs/proc/nommu.c
index ccfd99b..91cfd19 100644
--- a/fs/proc/nommu.c
+++ b/fs/proc/nommu.c
@@ -50,16 +50,16 @@ static int nommu_region_show(struct seq_file *m, struct
vm_region *region)
ino = inode->i_ino;
}
- seq_printf(m,
- "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu %n",
- region->vm_start,
- region->vm_end,
- flags & VM_READ ? 'r' : '-',
- flags & VM_WRITE ? 'w' : '-',
- flags & VM_EXEC ? 'x' : '-',
- flags & VM_MAYSHARE ? flags & VM_SHARED ? 'S' : 's' : 'p',
- ((loff_t)region->vm_pgoff) << PAGE_SHIFT,
- MAJOR(dev), MINOR(dev), ino, &len);
+ len = seq_printf(m, "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu ",
+ region->vm_start,
+ region->vm_end,
+ flags & VM_READ ? 'r' : '-',
+ flags & VM_WRITE ? 'w' : '-',
+ flags & VM_EXEC ? 'x' : '-',
+ flags & VM_MAYSHARE ?
+ flags & VM_SHARED ? 'S' : 's' : 'p',
+ ((loff_t)region->vm_pgoff) << PAGE_SHIFT,
+ MAJOR(dev), MINOR(dev), ino);
if (file) {
len = 25 + sizeof(void *) * 6 - len;
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 107d026..f84ee9f 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -286,15 +286,15 @@ show_map_vma(struct seq_file *m, struct vm_area_struct
*vma, int is_pid)
if (stack_guard_page_end(vma, end))
end -= PAGE_SIZE;
- seq_printf(m, "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu %n",
- start,
- end,
- flags & VM_READ ? 'r' : '-',
- flags & VM_WRITE ? 'w' : '-',
- flags & VM_EXEC ? 'x' : '-',
- flags & VM_MAYSHARE ? 's' : 'p',
- pgoff,
- MAJOR(dev), MINOR(dev), ino, &len);
+ len = seq_printf(m, "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu ",
+ start,
+ end,
+ flags & VM_READ ? 'r' : '-',
+ flags & VM_WRITE ? 'w' : '-',
+ flags & VM_EXEC ? 'x' : '-',
+ flags & VM_MAYSHARE ? 's' : 'p',
+ pgoff,
+ MAJOR(dev), MINOR(dev), ino);
/*
* Print the dentry name for named mappings, and a
diff --git a/fs/proc/task_nommu.c b/fs/proc/task_nommu.c
index 56123a6..1d7bbe5 100644
--- a/fs/proc/task_nommu.c
+++ b/fs/proc/task_nommu.c
@@ -155,16 +155,16 @@ static int nommu_vma_show(struct seq_file *m, struct
vm_area_struct *vma,
pgoff = (loff_t)vma->vm_pgoff << PAGE_SHIFT;
}
- seq_printf(m,
- "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu %n",
- vma->vm_start,
- vma->vm_end,
- flags & VM_READ ? 'r' : '-',
- flags & VM_WRITE ? 'w' : '-',
- flags & VM_EXEC ? 'x' : '-',
- flags & VM_MAYSHARE ? flags & VM_SHARED ? 'S' : 's' : 'p',
- pgoff,
- MAJOR(dev), MINOR(dev), ino, &len);
+ len = seq_printf(m, "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu ",
+ vma->vm_start,
+ vma->vm_end,
+ flags & VM_READ ? 'r' : '-',
+ flags & VM_WRITE ? 'w' : '-',
+ flags & VM_EXEC ? 'x' : '-',
+ flags & VM_MAYSHARE ?
+ flags & VM_SHARED ? 'S' : 's' : 'p',
+ pgoff,
+ MAJOR(dev), MINOR(dev), ino);
if (file) {
pad_len_spaces(m, len);
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 26559bd..43c2ea0 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -1683,18 +1683,19 @@ int vsnprintf(char *buf, size_t size, const char *fmt,
va_list args)
break;
case FORMAT_TYPE_NRCHARS: {
+ /* skip %n 's argument */
u8 qualifier = spec.qualifier;
+ void *skip_arg;
- if (qualifier == 'l') {
- long *ip = va_arg(args, long *);
- *ip = (str - buf);
- } else if (_tolower(qualifier) == 'z') {
- size_t *ip = va_arg(args, size_t *);
- *ip = (str - buf);
- } else {
- int *ip = va_arg(args, int *);
- *ip = (str - buf);
- }
+ WARN_ONCE(1, "Please remove ignored use of %%n in
'%s'\n",
+ old_fmt);
+
+ if (qualifier == 'l')
+ skip_arg = va_arg(args, long *);
+ else if (_tolower(qualifier) == 'z')
+ skip_arg = va_arg(args, size_t *);
+ else
+ skip_arg = va_arg(args, int *);
break;
}
diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index 3df6d3e..ddf1e9c 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -2537,24 +2537,20 @@ static int fib_route_seq_show(struct seq_file *seq,
void *v)
continue;
if (fi)
- seq_printf(seq,
- "%s\t%08X\t%08X\t%04X\t%d\t%u\t"
- "%d\t%08X\t%d\t%u\t%u%n",
- fi->fib_dev ? fi->fib_dev->name : "*",
- prefix,
- fi->fib_nh->nh_gw, flags, 0, 0,
- fi->fib_priority,
- mask,
- (fi->fib_advmss ?
- fi->fib_advmss + 40 : 0),
- fi->fib_window,
- fi->fib_rtt >> 3, &len);
+ len = seq_printf(seq,
"%s\t%08X\t%08X\t%04X\t%d\t%u\t%d\t%08X\t%d\t%u\t%u",
+ (fi->fib_dev ?
+ fi->fib_dev->name : "*"),
+ prefix,
+ fi->fib_nh->nh_gw, flags,
+ 0, 0, fi->fib_priority, mask,
+ (fi->fib_advmss ?
+ fi->fib_advmss + 40 : 0),
+ fi->fib_window,
+ fi->fib_rtt >> 3);
else
- seq_printf(seq,
- "*\t%08X\t%08X\t%04X\t%d\t%u\t"
- "%d\t%08X\t%d\t%u\t%u%n",
- prefix, 0, flags, 0, 0, 0,
- mask, 0, 0, 0, &len);
+ len = seq_printf(seq,
"*\t%08X\t%08X\t%04X\t%d\t%u\t%d\t%08X\t%d\t%u\t%u",
+ prefix, 0, flags, 0, 0, 0,
+ mask, 0, 0, 0);
seq_printf(seq, "%*s\n", 127 - len, "");
}
diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
index d7d9882..ac8d79f 100644
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -1081,16 +1081,15 @@ static void ping_v4_format_sock(struct sock *sp, struct
seq_file *f,
__u16 destp = ntohs(inet->inet_dport);
__u16 srcp = ntohs(inet->inet_sport);
- seq_printf(f, "%5d: %08X:%04X %08X:%04X"
- " %02X %08X:%08X %02X:%08lX %08X %5u %8d %lu %d %pK %d%n",
- bucket, src, srcp, dest, destp, sp->sk_state,
- sk_wmem_alloc_get(sp),
- sk_rmem_alloc_get(sp),
- 0, 0L, 0,
- from_kuid_munged(seq_user_ns(f), sock_i_uid(sp)),
- 0, sock_i_ino(sp),
- atomic_read(&sp->sk_refcnt), sp,
- atomic_read(&sp->sk_drops), len);
+ *len = seq_printf(f, "%5d: %08X:%04X %08X:%04X %02X %08X:%08X
%02X:%08lX %08X %5u %8d %lu %d %pK %d",
+ bucket, src, srcp, dest, destp, sp->sk_state,
+ sk_wmem_alloc_get(sp),
+ sk_rmem_alloc_get(sp),
+ 0, 0L, 0,
+ from_kuid_munged(seq_user_ns(f), sock_i_uid(sp)),
+ 0, sock_i_ino(sp),
+ atomic_read(&sp->sk_refcnt), sp,
+ atomic_read(&sp->sk_drops));
}
static int ping_v4_seq_show(struct seq_file *seq, void *v)
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index b14266b..1279c16 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2603,24 +2603,24 @@ static void get_openreq4(const struct sock *sk, const
struct request_sock *req,
const struct inet_request_sock *ireq = inet_rsk(req);
long delta = req->expires - jiffies;
- seq_printf(f, "%4d: %08X:%04X %08X:%04X"
- " %02X %08X:%08X %02X:%08lX %08X %5u %8d %u %d %pK%n",
- i,
- ireq->loc_addr,
- ntohs(inet_sk(sk)->inet_sport),
- ireq->rmt_addr,
- ntohs(ireq->rmt_port),
- TCP_SYN_RECV,
- 0, 0, /* could print option size, but that is af dependent. */
- 1, /* timers active (only the expire timer) */
- jiffies_delta_to_clock_t(delta),
- req->num_timeout,
- from_kuid_munged(seq_user_ns(f), uid),
- 0, /* non standard timer */
- 0, /* open_requests have no inode */
- atomic_read(&sk->sk_refcnt),
- req,
- len);
+ *len = seq_printf(f, "%4d: %08X:%04X %08X:%04X %02X %08X:%08X
%02X:%08lX %08X %5u %8d %u %d %pK",
+ i,
+ ireq->loc_addr,
+ ntohs(inet_sk(sk)->inet_sport),
+ ireq->rmt_addr,
+ ntohs(ireq->rmt_port),
+ TCP_SYN_RECV,
+ 0, 0, /* could print option size,
+ * but that is af dependent.
+ */
+ 1, /* timers active (only the expire timer) */
+ jiffies_delta_to_clock_t(delta),
+ req->num_timeout,
+ from_kuid_munged(seq_user_ns(f), uid),
+ 0, /* non standard timer */
+ 0, /* open_requests have no inode */
+ atomic_read(&sk->sk_refcnt),
+ req);
}
static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i, int *len)
@@ -2661,26 +2661,25 @@ static void get_tcp4_sock(struct sock *sk, struct
seq_file *f, int i, int *len)
*/
rx_queue = max_t(int, tp->rcv_nxt - tp->copied_seq, 0);
- seq_printf(f, "%4d: %08X:%04X %08X:%04X %02X %08X:%08X %02X:%08lX "
- "%08X %5u %8d %lu %d %pK %lu %lu %u %u %d%n",
- i, src, srcp, dest, destp, sk->sk_state,
- tp->write_seq - tp->snd_una,
- rx_queue,
- timer_active,
- jiffies_delta_to_clock_t(timer_expires - jiffies),
- icsk->icsk_retransmits,
- from_kuid_munged(seq_user_ns(f), sock_i_uid(sk)),
- icsk->icsk_probes_out,
- sock_i_ino(sk),
- atomic_read(&sk->sk_refcnt), sk,
- jiffies_to_clock_t(icsk->icsk_rto),
- jiffies_to_clock_t(icsk->icsk_ack.ato),
- (icsk->icsk_ack.quick << 1) | icsk->icsk_ack.pingpong,
- tp->snd_cwnd,
- sk->sk_state == TCP_LISTEN ?
- (fastopenq ? fastopenq->max_qlen : 0) :
- (tcp_in_initial_slowstart(tp) ? -1 : tp->snd_ssthresh),
- len);
+ *len = seq_printf(f, "%4d: %08X:%04X %08X:%04X %02X %08X:%08X
%02X:%08lX %08X %5u %8d %lu %d %pK %lu %lu %u %u %d",
+ i, src, srcp, dest, destp, sk->sk_state,
+ tp->write_seq - tp->snd_una,
+ rx_queue,
+ timer_active,
+ jiffies_delta_to_clock_t(timer_expires - jiffies),
+ icsk->icsk_retransmits,
+ from_kuid_munged(seq_user_ns(f), sock_i_uid(sk)),
+ icsk->icsk_probes_out,
+ sock_i_ino(sk),
+ atomic_read(&sk->sk_refcnt), sk,
+ jiffies_to_clock_t(icsk->icsk_rto),
+ jiffies_to_clock_t(icsk->icsk_ack.ato),
+ (icsk->icsk_ack.quick << 1) | icsk->icsk_ack.pingpong,
+ tp->snd_cwnd,
+ sk->sk_state == TCP_LISTEN ?
+ (fastopenq ? fastopenq->max_qlen : 0) :
+ (tcp_in_initial_slowstart(tp) ? -1 :
+ tp->snd_ssthresh));
}
static void get_timewait4_sock(const struct inet_timewait_sock *tw,
@@ -2695,11 +2694,10 @@ static void get_timewait4_sock(const struct
inet_timewait_sock *tw,
destp = ntohs(tw->tw_dport);
srcp = ntohs(tw->tw_sport);
- seq_printf(f, "%4d: %08X:%04X %08X:%04X"
- " %02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %pK%n",
- i, src, srcp, dest, destp, tw->tw_substate, 0, 0,
- 3, jiffies_delta_to_clock_t(delta), 0, 0, 0, 0,
- atomic_read(&tw->tw_refcnt), tw, len);
+ *len = seq_printf(f, "%4d: %08X:%04X %08X:%04X %02X %08X:%08X
%02X:%08lX %08X %5d %8d %d %d %pK",
+ i, src, srcp, dest, destp, tw->tw_substate, 0, 0,
+ 3, jiffies_delta_to_clock_t(delta), 0, 0, 0, 0,
+ atomic_read(&tw->tw_refcnt), tw);
}
#define TMPSZ 150
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 74d2c95..ddc24a2d 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -2158,16 +2158,15 @@ static void udp4_format_sock(struct sock *sp, struct
seq_file *f,
__u16 destp = ntohs(inet->inet_dport);
__u16 srcp = ntohs(inet->inet_sport);
- seq_printf(f, "%5d: %08X:%04X %08X:%04X"
- " %02X %08X:%08X %02X:%08lX %08X %5u %8d %lu %d %pK %d%n",
- bucket, src, srcp, dest, destp, sp->sk_state,
- sk_wmem_alloc_get(sp),
- sk_rmem_alloc_get(sp),
- 0, 0L, 0,
- from_kuid_munged(seq_user_ns(f), sock_i_uid(sp)),
- 0, sock_i_ino(sp),
- atomic_read(&sp->sk_refcnt), sp,
- atomic_read(&sp->sk_drops), len);
+ *len = seq_printf(f, "%5d: %08X:%04X %08X:%04X %02X %08X:%08X
%02X:%08lX %08X %5u %8d %lu %d %pK %d",
+ bucket, src, srcp, dest, destp, sp->sk_state,
+ sk_wmem_alloc_get(sp),
+ sk_rmem_alloc_get(sp),
+ 0, 0L, 0,
+ from_kuid_munged(seq_user_ns(f), sock_i_uid(sp)),
+ 0, sock_i_ino(sp),
+ atomic_read(&sp->sk_refcnt), sp,
+ atomic_read(&sp->sk_drops));
}
int udp4_seq_show(struct seq_file *seq, void *v)
diff --git a/net/phonet/socket.c b/net/phonet/socket.c
index 77e38f7..553f896 100644
--- a/net/phonet/socket.c
+++ b/net/phonet/socket.c
@@ -598,21 +598,20 @@ static int pn_sock_seq_show(struct seq_file *seq, void *v)
int len;
if (v == SEQ_START_TOKEN)
- seq_printf(seq, "%s%n", "pt loc rem rs st tx_queue rx_queue "
- " uid inode ref pointer drops", &len);
+ len = seq_puts(seq, "pt loc rem rs st tx_queue rx_queue uid
inode ref pointer drops");
else {
struct sock *sk = v;
struct pn_sock *pn = pn_sk(sk);
- seq_printf(seq, "%2d %04X:%04X:%02X %02X %08X:%08X %5d %lu "
- "%d %pK %d%n",
- sk->sk_protocol, pn->sobject, pn->dobject,
- pn->resource, sk->sk_state,
- sk_wmem_alloc_get(sk), sk_rmem_alloc_get(sk),
- from_kuid_munged(seq_user_ns(seq), sock_i_uid(sk)),
- sock_i_ino(sk),
- atomic_read(&sk->sk_refcnt), sk,
- atomic_read(&sk->sk_drops), &len);
+ len = seq_printf(seq, "%2d %04X:%04X:%02X %02X %08X:%08X %5d
%lu %d %pK %d",
+ sk->sk_protocol, pn->sobject, pn->dobject,
+ pn->resource, sk->sk_state,
+ sk_wmem_alloc_get(sk), sk_rmem_alloc_get(sk),
+ from_kuid_munged(seq_user_ns(seq),
+ sock_i_uid(sk)),
+ sock_i_ino(sk),
+ atomic_read(&sk->sk_refcnt), sk,
+ atomic_read(&sk->sk_drops));
}
seq_printf(seq, "%*s\n", 127 - len, "");
return 0;
@@ -788,15 +787,16 @@ static int pn_res_seq_show(struct seq_file *seq, void *v)
int len;
if (v == SEQ_START_TOKEN)
- seq_printf(seq, "%s%n", "rs uid inode", &len);
+ len = seq_puts(seq, "rs uid inode");
else {
struct sock **psk = v;
struct sock *sk = *psk;
- seq_printf(seq, "%02X %5u %lu%n",
- (int) (psk - pnres.sk),
- from_kuid_munged(seq_user_ns(seq), sock_i_uid(sk)),
- sock_i_ino(sk), &len);
+ len = seq_printf(seq, "%02X %5u %lu",
+ (int) (psk - pnres.sk),
+ from_kuid_munged(seq_user_ns(seq),
+ sock_i_uid(sk)),
+ sock_i_ino(sk));
}
seq_printf(seq, "%*s\n", 63 - len, "");
return 0;
diff --git a/net/sctp/objcnt.c b/net/sctp/objcnt.c
index 5ea573b..8034325 100644
--- a/net/sctp/objcnt.c
+++ b/net/sctp/objcnt.c
@@ -82,8 +82,9 @@ static int sctp_objcnt_seq_show(struct seq_file *seq, void *v)
int i, len;
i = (int)*(loff_t *)v;
- seq_printf(seq, "%s: %d%n", sctp_dbg_objcnt[i].label,
- atomic_read(sctp_dbg_objcnt[i].counter), &len);
+ len = seq_printf(seq, "%s: %d",
+ sctp_dbg_objcnt[i].label,
+ atomic_read(sctp_dbg_objcnt[i].counter));
seq_printf(seq, "%*s\n", 127 - len, "");
return 0;
}
--
1.8.1.2.459.gbcd45b4.dirty
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