proc/sysctl: fix the int overflow for jiffies conversion

gfreewind · torvalds · commit 63259457a2ee · 2017-05-08T17:15:10.000-07:00
do_proc_dointvec_jiffies_conv() uses LONG_MAX/HZ as the max value to avoid overflow. But actually the *valp is int type, so it still causes overflow. For example, echo 2147483647 > ./sys/net/ipv4/tcp_keepalive_time Then, cat ./sys/net/ipv4/tcp_keepalive_time The output is "-1", it is not expected. Now use INT_MAX/HZ as the max value instead LONG_MAX/HZ to fix it. Link: http://lkml.kernel.org/r/1490109532-9228-1-git-send-email-fgao@ikuai8.com Signed-off-by: Gao Feng <fgao@ikuai8.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
@@ -2576,7 +2576,7 @@ static int do_proc_dointvec_jiffies_conv(bool *negp, unsigned long *lvalp,
 					 int write, void *data)
 {
 	if (write) {
-		if (*lvalp > LONG_MAX / HZ)
+		if (*lvalp > INT_MAX / HZ)
 			return 1;
 		*valp = *negp ? -(*lvalp*HZ) : (*lvalp*HZ);
 	} else {

Original file line number	Diff line number	Diff line change
`@@ -2576,7 +2576,7 @@ static int do_proc_dointvec_jiffies_conv(bool negp, unsigned long lvalp,`
`2576`	`2576`	`int write, void *data)`
`2577`	`2577`	`{`
`2578`	`2578`	`if (write) {`
`2579`		`- if (*lvalp > LONG_MAX / HZ)`
	`2579`	`+ if (*lvalp > INT_MAX / HZ)`
`2580`	`2580`	`return 1;`
`2581`	`2581`	`valp = negp ? -(lvalpHZ) : (lvalpHZ);`
`2582`	`2582`	`} else {`