pstore: Fix buffer overflow while write offset equal to

buffer size In case new offset is equal to prz->buffer_size, it won't wrap at this time and will return old(overflow) value next time. Signed-off-by: Liu ShuoX <[email protected]> Acked-by: Kees Cook <[email protected]> Signed-off-by: Tony Luck <[email protected]> Signed-off-by: Pranav Vashi <[email protected]>
neobuddy89 · Jul 15, 2015 · ff1279e · ff1279e
1 parent 763ddbd
commit ff1279e
Showing 1 changed file with 2 additions and 2 deletions.
diff --git a/fs/pstore/ram_core.c b/fs/pstore/ram_core.c
@@ -54,7 +54,7 @@ static size_t buffer_start_add_atomic(struct persistent_ram_zone *prz, size_t a)
 	do {
 		old = atomic_read(&prz->buffer->start);
 		new = old + a;
-		while (unlikely(new > prz->buffer_size))
+		while (unlikely(new >= prz->buffer_size))
 			new -= prz->buffer_size;
 	} while (atomic_cmpxchg(&prz->buffer->start, old, new) != old);
 
@@ -91,7 +91,7 @@ static size_t buffer_start_add_locked(struct persistent_ram_zone *prz, size_t a)
 
 	old = atomic_read(&prz->buffer->start);
 	new = old + a;
-	while (unlikely(new > prz->buffer_size))
+	while (unlikely(new >= prz->buffer_size))
 		new -= prz->buffer_size;
 	atomic_set(&prz->buffer->start, new);