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[PATCH 32/38] fs/cachefiles: remove invalid checks

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  [PATCH 32/38] fs/cachefiles: remove invalid checks Andrzej Hajda <a.hajda@samsung.com> - 2015-09-21 15:40 +0200
    Re: [PATCH 32/38] fs/cachefiles: remove invalid checks David Howells <dhowells@redhat.com> - 2015-09-21 15:50 +0200
      Re: [PATCH 32/38] fs/cachefiles: remove invalid checks David Howells <dhowells@redhat.com> - 2015-09-21 18:20 +0200

#1229313 — [PATCH 32/38] fs/cachefiles: remove invalid checks

Unsigned values cannot be lesser than zero.

The problem has been detected using proposed semantic patch
scripts/coccinelle/tests/unsigned_lesser_than_zero.cocci [1].

[1]: http://permalink.gmane.org/gmane.linux.kernel/2038576

Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
---
 fs/cachefiles/bind.c   | 9 +++------
 fs/cachefiles/daemon.c | 6 +++---
 2 files changed, 6 insertions(+), 9 deletions(-)

diff --git a/fs/cachefiles/bind.c b/fs/cachefiles/bind.c
index 6af790f..6b50c88 100644
--- a/fs/cachefiles/bind.c
+++ b/fs/cachefiles/bind.c
@@ -39,13 +39,10 @@ int cachefiles_daemon_bind(struct cachefiles_cache *cache, char *args)
 	       args);
 
 	/* start by checking things over */
-	ASSERT(cache->fstop_percent >= 0 &&
-	       cache->fstop_percent < cache->fcull_percent &&
-	       cache->fcull_percent < cache->frun_percent &&
-	       cache->frun_percent  < 100);
+	ASSERT(cache->fstop_percent < cache->fcull_percent &&
+	       cache->fcull_percent < cache->frun_percent);
 
-	ASSERT(cache->bstop_percent >= 0 &&
-	       cache->bstop_percent < cache->bcull_percent &&
+	ASSERT(cache->bstop_percent < cache->bcull_percent &&
 	       cache->bcull_percent < cache->brun_percent &&
 	       cache->brun_percent  < 100);
 
diff --git a/fs/cachefiles/daemon.c b/fs/cachefiles/daemon.c
index f601def..996ecd2 100644
--- a/fs/cachefiles/daemon.c
+++ b/fs/cachefiles/daemon.c
@@ -222,7 +222,7 @@ static ssize_t cachefiles_daemon_write(struct file *file,
 	if (test_bit(CACHEFILES_DEAD, &cache->flags))
 		return -EIO;
 
-	if (datalen < 0 || datalen > PAGE_SIZE - 1)
+	if (datalen > PAGE_SIZE - 1)
 		return -EOPNOTSUPP;
 
 	/* drag the command string into the kernel so we can parse it */
@@ -385,7 +385,7 @@ static int cachefiles_daemon_fstop(struct cachefiles_cache *cache, char *args)
 	if (args[0] != '%' || args[1] != '\0')
 		return -EINVAL;
 
-	if (fstop < 0 || fstop >= cache->fcull_percent)
+	if (fstop >= cache->fcull_percent)
 		return cachefiles_daemon_range_error(cache, args);
 
 	cache->fstop_percent = fstop;
@@ -457,7 +457,7 @@ static int cachefiles_daemon_bstop(struct cachefiles_cache *cache, char *args)
 	if (args[0] != '%' || args[1] != '\0')
 		return -EINVAL;
 
-	if (bstop < 0 || bstop >= cache->bcull_percent)
+	if (bstop >= cache->bcull_percent)
 		return cachefiles_daemon_range_error(cache, args);
 
 	cache->bstop_percent = bstop;
-- 
1.9.1

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#1229358

Andrzej Hajda <a.hajda@samsung.com> wrote:

> The problem has been detected using proposed semantic patch
> scripts/coccinelle/tests/unsigned_lesser_than_zero.cocci [1].

This is a problem in your test.  There's no actual problem with the code.

> -	ASSERT(cache->fstop_percent >= 0 &&

This is fine.  The compiler should just ignore it.

> -	       cache->fstop_percent < cache->fcull_percent &&
> -	       cache->fcull_percent < cache->frun_percent &&
> -	       cache->frun_percent  < 100);
> +	ASSERT(cache->fstop_percent < cache->fcull_percent &&
> +	       cache->fcull_percent < cache->frun_percent);

You've lost the upper bound check.

> -	if (datalen < 0 || datalen > PAGE_SIZE - 1)
> -	if (fstop < 0 || fstop >= cache->fcull_percent)
> -	if (bstop < 0 || bstop >= cache->bcull_percent)

These are all fine.  The compiler should just ignore them.

David
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#1229529

David Howells <dhowells@redhat.com> wrote:

> > -	ASSERT(cache->fstop_percent >= 0 &&
> 
> This is fine.  The compiler should just ignore it.

By fine, I mean fine as-is.  It shouldn't need changing.

David
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