diff options
| author | Olav Haugan <ohaugan@codeaurora.org> | 2013-11-22 09:30:41 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-12-04 10:55:47 -0800 |
| commit | 6871b98011fd07991f9259c9be339b1bde34d527 (patch) | |
| tree | b6cf86e9ee4cf9610a0389d388aad8a71acdbfff /drivers/staging | |
| parent | 51de4ecd7c25fae75eb8d0936a443119e13384f9 (diff) | |
staging: zsmalloc: Ensure handle is never 0 on success
commit 67296874eb1cc80317bf2a8fba22b494e21eb29b upstream.
zsmalloc encodes a handle using the pfn and an object
index. On hardware platforms with physical memory starting
at 0x0 the pfn can be 0. This causes the encoded handle to be
0 and is incorrectly interpreted as an allocation failure.
This issue affects all current and future SoCs with physical
memory starting at 0x0. All MSM8974 SoCs which includes
Google Nexus 5 devices are affected.
To prevent this false error we ensure that the encoded handle
will not be 0 when allocation succeeds.
Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/staging')
| -rw-r--r-- | drivers/staging/zsmalloc/zsmalloc-main.c | 17 |
1 files changed, 13 insertions, 4 deletions
diff --git a/drivers/staging/zsmalloc/zsmalloc-main.c b/drivers/staging/zsmalloc/zsmalloc-main.c index f82f7e69c8a5..288f58252a18 100644 --- a/drivers/staging/zsmalloc/zsmalloc-main.c +++ b/drivers/staging/zsmalloc/zsmalloc-main.c @@ -430,7 +430,12 @@ static struct page *get_next_page(struct page *page) return next; } -/* Encode <page, obj_idx> as a single handle value */ +/* + * Encode <page, obj_idx> as a single handle value. + * On hardware platforms with physical memory starting at 0x0 the pfn + * could be 0 so we ensure that the handle will never be 0 by adjusting the + * encoded obj_idx value before encoding. + */ static void *obj_location_to_handle(struct page *page, unsigned long obj_idx) { unsigned long handle; @@ -441,17 +446,21 @@ static void *obj_location_to_handle(struct page *page, unsigned long obj_idx) } handle = page_to_pfn(page) << OBJ_INDEX_BITS; - handle |= (obj_idx & OBJ_INDEX_MASK); + handle |= ((obj_idx + 1) & OBJ_INDEX_MASK); return (void *)handle; } -/* Decode <page, obj_idx> pair from the given object handle */ +/* + * Decode <page, obj_idx> pair from the given object handle. We adjust the + * decoded obj_idx back to its original value since it was adjusted in + * obj_location_to_handle(). + */ static void obj_handle_to_location(unsigned long handle, struct page **page, unsigned long *obj_idx) { *page = pfn_to_page(handle >> OBJ_INDEX_BITS); - *obj_idx = handle & OBJ_INDEX_MASK; + *obj_idx = (handle & OBJ_INDEX_MASK) - 1; } static unsigned long obj_idx_to_offset(struct page *page, |