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 <shuox.liu@intel.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
diff --git a/fs/pstore/ram_core.c b/fs/pstore/ram_core.c
index de272d4..ff7e3d4 100644
--- a/fs/pstore/ram_core.c
+++ b/fs/pstore/ram_core.c
@@ -54,7 +54,7 @@
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 @@
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);