From 22883973244b1caaa26f9c6171a41ba843c8d4bd Mon Sep 17 00:00:00 2001 From: "Kirill A. Shutemov" Date: Wed, 9 Aug 2023 17:46:00 +0300 Subject: [PATCH] mm: Fix access_remote_vm() regression on tagged addresses GDB uses /proc/PID/mem to access memory of the target process. GDB doesn't untag addresses manually, but relies on kernel to do the right thing. mem_rw() of procfs uses access_remote_vm() to get data from the target process. It worked fine until recent changes in __access_remote_vm() that now checks if there's VMA at target address using raw address. Untag the address before looking up the VMA. Signed-off-by: Kirill A. Shutemov Reported-by: Christina Schimpe Fixes: eee9c708cc89 ("gup: avoid stack expansion warning for known-good case") Cc: stable@vger.kernel.org Signed-off-by: Linus Torvalds --- mm/memory.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/mm/memory.c b/mm/memory.c index 603b2f419948..1ec1ef3418bf 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -5705,6 +5705,9 @@ int __access_remote_vm(struct mm_struct *mm, unsigned long addr, void *buf, if (mmap_read_lock_killable(mm)) return 0; + /* Untag the address before looking up the VMA */ + addr = untagged_addr_remote(mm, addr); + /* Avoid triggering the temporary warning in __get_user_pages */ if (!vma_lookup(mm, addr) && !expand_stack(mm, addr)) return 0;