6.1-stable review patch. If anyone has any objections, please let me know.
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From: Sebastian Ott sebott@redhat.com
commit e0f81ab1e4f42ffece6440dc78f583eb352b9a71 upstream.
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 sebott@redhat.com Signed-off-by: Kees Cook keescook@chromium.org Reviewed-by: Liam R. Howlett Liam.Howlett@oracle.com Cc: Yu Zhao yuzhao@google.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- mm/mmap.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
--- a/mm/mmap.c +++ b/mm/mmap.c @@ -3147,13 +3147,13 @@ int vm_brk_flags(unsigned long addr, uns 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;