[PATCH] mm: Replace-simple_strtoul-with-kstrtoul

[PATCH] mm: Replace-simple_strtoul-with-kstrtoul

[Manjeet Pawar]

simple_strtoul() is obselete now, so using newer function kstrtoul()

Signed-off-by: Manjeet Pawar <manjeet.p@samsung.com>
Signed-off-by: Vinay Kumar Rijhwani <v.rijhwani@samsung.com>
Signed-off-by: Rohit Thapliyal <r.thapliyal@samsung.com>
---
 mm/page_alloc.c |  3 +--
 mm/shmem.c      | 11 +++++------
 2 files changed, 6 insertions(+), 8 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 77e4d3c..f9d812e 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -7197,9 +7197,8 @@ int percpu_pagelist_fraction_sysctl_handler(struct ctl_table *table, int write,
 
 static int __init set_hashdist(char *str)
 {
-	if (!str)
+	if (!str || kstrtoul(str, 0, (unsigned long *)&hashdist))
 		return 0;
-	hashdist = simple_strtoul(str, &str, 0);
 	return 1;
 }
 __setup("hashdist=", set_hashdist);
diff --git a/mm/shmem.c b/mm/shmem.c
index 07a1d22..bf7d905 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -3470,6 +3470,7 @@ static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo,
 	struct mempolicy *mpol = NULL;
 	uid_t uid;
 	gid_t gid;
+	unsigned long mode;
 
 	while (options != NULL) {
 		this_char = options;
@@ -3522,14 +3523,13 @@ static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo,
 		} else if (!strcmp(this_char,"mode")) {
 			if (remount)
 				continue;
-			sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777;
-			if (*rest)
+			if (kstrtoul(value, 8, &mode))
 				goto bad_val;
+			sbinfo->mode = mode & 07777;
 		} else if (!strcmp(this_char,"uid")) {
 			if (remount)
 				continue;
-			uid = simple_strtoul(value, &rest, 0);
-			if (*rest)
+			if (kstrtoul(value, 0, (unsigned long *)&uid))
 				goto bad_val;
 			sbinfo->uid = make_kuid(current_user_ns(), uid);
 			if (!uid_valid(sbinfo->uid))
@@ -3537,8 +3537,7 @@ static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo,
 		} else if (!strcmp(this_char,"gid")) {
 			if (remount)
 				continue;
-			gid = simple_strtoul(value, &rest, 0);
-			if (*rest)
+			if (kstrtoul(value, 0, (unsigned long *)&gid))
 				goto bad_val;
 			sbinfo->gid = make_kgid(current_user_ns(), gid);
 			if (!gid_valid(sbinfo->gid))
-- 
1.9.1

Re: [PATCH] mm: Replace-simple_strtoul-with-kstrtoul

[Matthew Wilcox]

On Thu, Nov 09, 2017 at 04:58:18PM +0530, Manjeet Pawar wrote:
> simple_strtoul() is obselete now, so using newer function kstrtoul()
> 
> Signed-off-by: Manjeet Pawar <manjeet.p@samsung.com>
> Signed-off-by: Vinay Kumar Rijhwani <v.rijhwani@samsung.com>
> Signed-off-by: Rohit Thapliyal <r.thapliyal@samsung.com>

NAK NAK NAK.

You haven't tested this on a 64-bit big-endian machine.

>  static int __init set_hashdist(char *str)
>  {
> -	if (!str)
> +	if (!str || kstrtoul(str, 0, (unsigned long *)&hashdist))
>  		return 0;
> -	hashdist = simple_strtoul(str, &str, 0);
>  	return 1;

The context missing from this patch is:

int hashdist = HASHDIST_DEFAULT;

So you're taking the address of an int and passing it to a function
which is expecting a pointer to an unsigned long.  That works on a
32-bit machine because ints and longs are the same size.  On a 64-bit
little-endian machine, the bits are in the right place, but kstrtoul()
will overwrite the 32 bits after the int with zeroes.  On a 64-bit
big-endian machine, you'll overwrite the int that you're pointing to
with zeroes and the 32 bits after the int will have the data you're
looking for.

There's a kstrtoint().  Why would you not just use that?

Also, I'm shocked that this went through a chain of three different
sign-offs with nobody noticing the problem.  Do none of you understand C?

(similar problems snipped).