6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sebastian Ott <sebott@xxxxxxxxxx> 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@xxxxxxxxxx Fixes: 2e7ce7d354f2 ("mm/mmap: change do_brk_flags() to expand existing VMA and add do_brk_munmap()") Signed-off-by: Sebastian Ott <sebott@xxxxxxxxxx> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> Reviewed-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx> Cc: Yu Zhao <yuzhao@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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;
