The patch titled
Subject: treewide: remove false-positive VLAs when using max()
has been added to the -mm tree. Its filename is
remove-false-positive-vlas-when-using-max.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/remove-false-positive-vlas-when-using-max.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/remove-false-positive-vlas-when-using-max.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Kees Cook <keescook@xxxxxxxxxxxx>
Subject: treewide: remove false-positive VLAs when using max()
As part of removing VLAs from the kernel[1], we want to build with -Wvla,
but it is overly pessimistic and only accepts constant expressions for
stack array sizes, instead of also constant values. The max() macro
triggers the warning, so this refactors these uses of max() to use the new
const_max() instead.
[1] https://lkml.org/lkml/2018/3/7/621
Link: http://lkml.kernel.org/r/1521143266-31350-3-git-send-email-keescook@xxxxxxxxxxxx
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Cc: Miguel Ojeda <miguel.ojeda.sandonis@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: David Laight <David.Laight@xxxxxxxxxx>
Cc: Ian Abbott <abbotti@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/input/touchscreen/cyttsp4_core.c | 2 +-
fs/btrfs/tree-checker.c | 3 ++-
lib/vsprintf.c | 4 ++--
net/ipv4/proc.c | 8 ++++----
net/ipv6/proc.c | 10 ++++------
5 files changed, 13 insertions(+), 14 deletions(-)
diff -puN drivers/input/touchscreen/cyttsp4_core.c~remove-false-positive-vlas-when-using-max drivers/input/touchscreen/cyttsp4_core.c
--- a/drivers/input/touchscreen/cyttsp4_core.c~remove-false-positive-vlas-when-using-max
+++ a/drivers/input/touchscreen/cyttsp4_core.c
@@ -868,7 +868,7 @@ static void cyttsp4_get_mt_touches(struc
struct cyttsp4_touch tch;
int sig;
int i, j, t = 0;
- int ids[max(CY_TMA1036_MAX_TCH, CY_TMA4XX_MAX_TCH)];
+ int ids[const_max(CY_TMA1036_MAX_TCH, CY_TMA4XX_MAX_TCH)];
memset(ids, 0, si->si_ofs.tch_abs[CY_TCH_T].max * sizeof(int));
for (i = 0; i < num_cur_tch; i++) {
diff -puN fs/btrfs/tree-checker.c~remove-false-positive-vlas-when-using-max fs/btrfs/tree-checker.c
--- a/fs/btrfs/tree-checker.c~remove-false-positive-vlas-when-using-max
+++ a/fs/btrfs/tree-checker.c
@@ -341,7 +341,8 @@ static int check_dir_item(struct btrfs_r
*/
if (key->type == BTRFS_DIR_ITEM_KEY ||
key->type == BTRFS_XATTR_ITEM_KEY) {
- char namebuf[max(BTRFS_NAME_LEN, XATTR_NAME_MAX)];
+ char namebuf[const_max(BTRFS_NAME_LEN,
+ XATTR_NAME_MAX)];
read_extent_buffer(leaf, namebuf,
(unsigned long)(di + 1), name_len);
diff -puN lib/vsprintf.c~remove-false-positive-vlas-when-using-max lib/vsprintf.c
--- a/lib/vsprintf.c~remove-false-positive-vlas-when-using-max
+++ a/lib/vsprintf.c
@@ -754,8 +754,8 @@ char *resource_string(char *buf, char *e
#define FLAG_BUF_SIZE (2 * sizeof(res->flags))
#define DECODED_BUF_SIZE sizeof("[mem - 64bit pref window disabled]")
#define RAW_BUF_SIZE sizeof("[mem - flags 0x]")
- char sym[max(2*RSRC_BUF_SIZE + DECODED_BUF_SIZE,
- 2*RSRC_BUF_SIZE + FLAG_BUF_SIZE + RAW_BUF_SIZE)];
+ char sym[const_max(2*RSRC_BUF_SIZE + DECODED_BUF_SIZE,
+ 2*RSRC_BUF_SIZE + FLAG_BUF_SIZE + RAW_BUF_SIZE)];
char *p = sym, *pend = sym + sizeof(sym);
int decode = (fmt[0] == 'R') ? 1 : 0;
diff -puN net/ipv4/proc.c~remove-false-positive-vlas-when-using-max net/ipv4/proc.c
--- a/net/ipv4/proc.c~remove-false-positive-vlas-when-using-max
+++ a/net/ipv4/proc.c
@@ -46,7 +46,7 @@
#include <net/sock.h>
#include <net/raw.h>
-#define TCPUDP_MIB_MAX max_t(u32, UDP_MIB_MAX, TCP_MIB_MAX)
+#define TCPUDP_MIB_MAX const_max(UDP_MIB_MAX, TCP_MIB_MAX)
/*
* Report socket allocation statistics [mea@xxxxxx]
@@ -404,7 +404,7 @@ static int snmp_seq_show_tcp_udp(struct
struct net *net = seq->private;
int i;
- memset(buff, 0, TCPUDP_MIB_MAX * sizeof(unsigned long));
+ memset(buff, 0, sizeof(buff));
seq_puts(seq, "\nTcp:");
for (i = 0; snmp4_tcp_list[i].name; i++)
@@ -421,7 +421,7 @@ static int snmp_seq_show_tcp_udp(struct
seq_printf(seq, " %lu", buff[i]);
}
- memset(buff, 0, TCPUDP_MIB_MAX * sizeof(unsigned long));
+ memset(buff, 0, sizeof(buff));
snmp_get_cpu_field_batch(buff, snmp4_udp_list,
net->mib.udp_statistics);
@@ -432,7 +432,7 @@ static int snmp_seq_show_tcp_udp(struct
for (i = 0; snmp4_udp_list[i].name; i++)
seq_printf(seq, " %lu", buff[i]);
- memset(buff, 0, TCPUDP_MIB_MAX * sizeof(unsigned long));
+ memset(buff, 0, sizeof(buff));
/* the UDP and UDP-Lite MIBs are the same */
seq_puts(seq, "\nUdpLite:");
diff -puN net/ipv6/proc.c~remove-false-positive-vlas-when-using-max net/ipv6/proc.c
--- a/net/ipv6/proc.c~remove-false-positive-vlas-when-using-max
+++ a/net/ipv6/proc.c
@@ -30,10 +30,8 @@
#include <net/transp_v6.h>
#include <net/ipv6.h>
-#define MAX4(a, b, c, d) \
- max_t(u32, max_t(u32, a, b), max_t(u32, c, d))
-#define SNMP_MIB_MAX MAX4(UDP_MIB_MAX, TCP_MIB_MAX, \
- IPSTATS_MIB_MAX, ICMP_MIB_MAX)
+#define SNMP_MIB_MAX const_max(const_max(UDP_MIB_MAX, TCP_MIB_MAX), \
+ const_max(IPSTATS_MIB_MAX, ICMP_MIB_MAX))
static int sockstat6_seq_show(struct seq_file *seq, void *v)
{
@@ -199,7 +197,7 @@ static void snmp6_seq_show_item(struct s
int i;
if (pcpumib) {
- memset(buff, 0, sizeof(unsigned long) * SNMP_MIB_MAX);
+ memset(buff, 0, sizeof(buff));
snmp_get_cpu_field_batch(buff, itemlist, pcpumib);
for (i = 0; itemlist[i].name; i++)
@@ -218,7 +216,7 @@ static void snmp6_seq_show_item64(struct
u64 buff64[SNMP_MIB_MAX];
int i;
- memset(buff64, 0, sizeof(u64) * SNMP_MIB_MAX);
+ memset(buff64, 0, sizeof(buff64));
snmp_get_cpu_field64_batch(buff64, itemlist, mib, syncpoff);
for (i = 0; itemlist[i].name; i++)
_
Patches currently in -mm which might be from keescook@xxxxxxxxxxxx are
taint-convert-to-indexed-initialization.patch
taint-consolidate-documentation.patch
taint-add-taint-for-randstruct.patch
kernelh-introduce-const_max-for-vla-removal.patch
remove-false-positive-vlas-when-using-max.patch
test_bitmap-do-not-accidentally-use-stack-vla.patch
fork-unconditionally-clear-stack-on-fork.patch
exec-pass-stack-rlimit-into-mm-layout-functions.patch
exec-introduce-finalize_exec-before-start_thread.patch
exec-pin-stack-limit-during-exec.patch
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