It is of critical importance to check the return results on VMA merge (and
split), failure to do so can result in use-after-free's. This bug has
recurred, so have the compiler enforce this check to prevent any future
repetition.
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>
---
mm/vma.c | 8 +++++---
mm/vma.h | 26 +++++++++++++++-----------
2 files changed, 20 insertions(+), 14 deletions(-)
diff --git a/mm/vma.c b/mm/vma.c
index a06747845cac..543c102b4062 100644
--- a/mm/vma.c
+++ b/mm/vma.c
@@ -447,8 +447,9 @@ void unmap_region(struct ma_state *mas, struct vm_area_struct *vma,
* has already been checked or doesn't make sense to fail.
* VMA Iterator will point to the original VMA.
*/
-static int __split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma,
- unsigned long addr, int new_below)
+static __must_check int
+__split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma,
+ unsigned long addr, int new_below)
{
struct vma_prepare vp;
struct vm_area_struct *new;
@@ -710,7 +711,8 @@ static bool can_merge_remove_vma(struct vm_area_struct *vma)
* - The caller must hold a WRITE lock on the mm_struct->mmap_lock.
* - vmi must be positioned within [@vmg->vma->vm_start, @vmg->vma->vm_end).
*/
-static struct vm_area_struct *vma_merge_existing_range(struct vma_merge_struct *vmg)
+static __must_check struct vm_area_struct *vma_merge_existing_range(
+ struct vma_merge_struct *vmg)
{
struct vm_area_struct *vma = vmg->vma;
struct vm_area_struct *prev = vmg->prev;
diff --git a/mm/vma.h b/mm/vma.h
index 295d44ea54db..61ed044b6145 100644
--- a/mm/vma.h
+++ b/mm/vma.h
@@ -139,9 +139,10 @@ void validate_mm(struct mm_struct *mm);
#define validate_mm(mm) do { } while (0)
#endif
-int vma_expand(struct vma_merge_struct *vmg);
-int vma_shrink(struct vma_iterator *vmi, struct vm_area_struct *vma,
- unsigned long start, unsigned long end, pgoff_t pgoff);
+__must_check int vma_expand(struct vma_merge_struct *vmg);
+__must_check int vma_shrink(struct vma_iterator *vmi,
+ struct vm_area_struct *vma,
+ unsigned long start, unsigned long end, pgoff_t pgoff);
static inline int vma_iter_store_gfp(struct vma_iterator *vmi,
struct vm_area_struct *vma, gfp_t gfp)
@@ -174,13 +175,14 @@ void unmap_region(struct ma_state *mas, struct vm_area_struct *vma,
struct vm_area_struct *prev, struct vm_area_struct *next);
/* We are about to modify the VMA's flags. */
-struct vm_area_struct *vma_modify_flags(struct vma_iterator *vmi,
+__must_check struct vm_area_struct
+*vma_modify_flags(struct vma_iterator *vmi,
struct vm_area_struct *prev, struct vm_area_struct *vma,
unsigned long start, unsigned long end,
unsigned long new_flags);
/* We are about to modify the VMA's flags and/or anon_name. */
-struct vm_area_struct
+__must_check struct vm_area_struct
*vma_modify_flags_name(struct vma_iterator *vmi,
struct vm_area_struct *prev,
struct vm_area_struct *vma,
@@ -190,7 +192,7 @@ struct vm_area_struct
struct anon_vma_name *new_name);
/* We are about to modify the VMA's memory policy. */
-struct vm_area_struct
+__must_check struct vm_area_struct
*vma_modify_policy(struct vma_iterator *vmi,
struct vm_area_struct *prev,
struct vm_area_struct *vma,
@@ -198,7 +200,7 @@ struct vm_area_struct
struct mempolicy *new_pol);
/* We are about to modify the VMA's flags and/or uffd context. */
-struct vm_area_struct
+__must_check struct vm_area_struct
*vma_modify_flags_uffd(struct vma_iterator *vmi,
struct vm_area_struct *prev,
struct vm_area_struct *vma,
@@ -206,11 +208,13 @@ struct vm_area_struct
unsigned long new_flags,
struct vm_userfaultfd_ctx new_ctx);
-struct vm_area_struct *vma_merge_new_range(struct vma_merge_struct *vmg);
+__must_check struct vm_area_struct
+*vma_merge_new_range(struct vma_merge_struct *vmg);
-struct vm_area_struct *vma_merge_extend(struct vma_iterator *vmi,
- struct vm_area_struct *vma,
- unsigned long delta);
+__must_check struct vm_area_struct
+*vma_merge_extend(struct vma_iterator *vmi,
+ struct vm_area_struct *vma,
+ unsigned long delta);
void unlink_file_vma_batch_init(struct unlink_vma_file_batch *vb);
--
2.47.1
