Commit f6899bc0 authored by Nikita Ermakov's avatar Nikita Ermakov Committed by Linus Torvalds
Browse files

mm/msync: exit early when the flags is an MS_ASYNC and start < vm_start 

If an unmapped region was found and the flag is MS_ASYNC (without
MS_INVALIDATE) there is nothing to do and the result would be always
-ENOMEM, so return immediately.

Link: https://lkml.kernel.org/r/20201025092901.56399-1-sh1r4s3@mail.si-head.nl


Signed-off-by: default avatarNikita Ermakov <sh1r4s3@mail.si-head.nl>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4b17f030

mm/msync.c

+5 −1
Original line number Diff line number Diff line
@@ -55,7 +55,9 @@ SYSCALL_DEFINE3(msync, unsigned long, start, size_t, len, int, flags) 
		goto out;

	/*

	 * If the interval [start,end) covers some unmapped address ranges,

	 * just ignore them, but return -ENOMEM at the end.

	 * just ignore them, but return -ENOMEM at the end. Besides, if the

	 * flag is MS_ASYNC (w/o MS_INVALIDATE) the result would be -ENOMEM

	 * anyway and there is nothing left to do, so return immediately.

	 */

	mmap_read_lock(mm);

	vma = find_vma(mm, start);
@@ -69,6 +71,8 @@ SYSCALL_DEFINE3(msync, unsigned long, start, size_t, len, int, flags) 
			goto out_unlock;

		/* Here start < vma->vm_end. */

		if (start < vma->vm_start) {

			if (flags == MS_ASYNC)

				goto out_unlock;

			start = vma->vm_start;

			if (start >= end)

				goto out_unlock;