| Message ID | 20230929171937.work.697-kees@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm: Fix vm_brk_flags() to not bail out while holding lock | expand |
* Kees Cook <keescook@chromium.org> [230929 13:19]: > From: Sebastian Ott <sebott@redhat.com> > > 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. > > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Liam R. Howlett <Liam.Howlett@Oracle.com> > Cc: Yu Zhao <yuzhao@google.com> > Cc: linux-mm@kvack.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> > --- > mm/mmap.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/mm/mmap.c b/mm/mmap.c > index 34d2337ace59..c8996fe847c9 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; > -- > 2.34.1 >
diff --git a/mm/mmap.c b/mm/mmap.c index 34d2337ace59..c8996fe847c9 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;