From e0f81ab1e4f42ffece6440dc78f583eb352b9a71 Mon Sep 17 00:00:00 2001 From: Sebastian Ott Date: Fri, 29 Sep 2023 10:19:41 -0700 Subject: mm: fix vm_brk_flags() to not bail out while holding lock Calling vm_brk_flags() with flags set other than VM_EXEC will exit the function without releasing the mmap_write_lock. Just do the sanity check before the lock is acquired. This doesn't fix an actual issue since no caller sets a flag other than VM_EXEC. Link: https://lkml.kernel.org/r/20230929171937.work.697-kees@kernel.org Fixes: 2e7ce7d354f2 ("mm/mmap: change do_brk_flags() to expand existing VMA and add do_brk_munmap()") Signed-off-by: Sebastian Ott Signed-off-by: Kees Cook Reviewed-by: Liam R. Howlett Cc: Yu Zhao Signed-off-by: Andrew Morton --- mm/mmap.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'mm/mmap.c') diff --git a/mm/mmap.c b/mm/mmap.c index b56a7f0c9f85..7ed286662839 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -3143,13 +3143,13 @@ int vm_brk_flags(unsigned long addr, unsigned long request, unsigned long flags) if (!len) return 0; - if (mmap_write_lock_killable(mm)) - return -EINTR; - /* Until we need other flags, refuse anything except VM_EXEC. */ if ((flags & (~VM_EXEC)) != 0) return -EINVAL; + if (mmap_write_lock_killable(mm)) + return -EINTR; + ret = check_brk_limits(addr, len); if (ret) goto limits_failed; -- cgit