Commit 78d2d32f authored by Carlos Llamas's avatar Carlos Llamas Committed by Andrew Morton
Browse files

mm/mremap: fix regression in vrm->new_addr check 

Commit 3215eace ("mm/mremap: refactor initial parameter sanity
checks") moved the sanity check for vrm->new_addr from mremap_to() to
check_mremap_params().

However, this caused a regression as vrm->new_addr is now checked even
when MREMAP_FIXED and MREMAP_DONTUNMAP flags are not specified.  In this
case, vrm->new_addr can be garbage and create unexpected failures.

Fix this by moving the new_addr check after the vrm_implies_new_addr()
guard.  This ensures that the new_addr is only checked when the user has
specified one explicitly.

Link: https://lkml.kernel.org/r/20250828142657.770502-1-cmllamas@google.com


Fixes: 3215eace ("mm/mremap: refactor initial parameter sanity checks")
Signed-off-by: default avatarCarlos Llamas <cmllamas@google.com>
Reviewed-by: default avatarLiam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: default avatarVlastimil Babka <vbabka@suse.cz>
Reviewed-by: default avatarLorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Carlos Llamas <cmllamas@google.com>
Cc: Jann Horn <jannh@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 7989fdce

mm/mremap.c

+6 −3
Original line number Diff line number Diff line
@@ -1774,15 +1774,18 @@ static unsigned long check_mremap_params(struct vma_remap_struct *vrm) 
	if (!vrm->new_len)

		return -EINVAL;



	/* Is the new length or address silly? */

	if (vrm->new_len > TASK_SIZE ||

	    vrm->new_addr > TASK_SIZE - vrm->new_len)

	/* Is the new length silly? */

	if (vrm->new_len > TASK_SIZE)

		return -EINVAL;



	/* Remainder of checks are for cases with specific new_addr. */

	if (!vrm_implies_new_addr(vrm))

		return 0;



	/* Is the new address silly? */

	if (vrm->new_addr > TASK_SIZE - vrm->new_len)

		return -EINVAL;



	/* The new address must be page-aligned. */

	if (offset_in_page(vrm->new_addr))

		return -EINVAL;