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mm: enforce __must_check on VMA merge and split

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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.

Link: https://lkml.kernel.org/r/20241206225036.273103-1-lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Jann Horn <jannh@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Lorenzo Stoakes 2024-12-06 22:50:36 +00:00 committed by Andrew Morton
parent 7f1e9a24ec
commit e6a86f6fe9
2 changed files with 20 additions and 14 deletions
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6
mm/vma.c
View File

@ -447,7 +447,8 @@ 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,
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;
@ -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;

20
mm/vma.h
View File

@ -139,8 +139,9 @@ 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,
__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,
@ -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,
@ -206,9 +208,11 @@ 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,
__must_check struct vm_area_struct
*vma_merge_extend(struct vma_iterator *vmi,
struct vm_area_struct *vma,
unsigned long delta);