From 2aea94ac14d1e0a8ae9e34febebe208213ba72f7 Mon Sep 17 00:00:00 2001 From: Max Filippov Date: Wed, 20 Mar 2024 11:26:07 -0700 Subject: exec: Fix NOMMU linux_binprm::exec in transfer_args_to_stack() In NOMMU kernel the value of linux_binprm::p is the offset inside the temporary program arguments array maintained in separate pages in the linux_binprm::page. linux_binprm::exec being a copy of linux_binprm::p thus must be adjusted when that array is copied to the user stack. Without that adjustment the value passed by the NOMMU kernel to the ELF program in the AT_EXECFN entry of the aux array doesn't make any sense and it may break programs that try to access memory pointed to by that entry. Adjust linux_binprm::exec before the successful return from the transfer_args_to_stack(). Cc: Fixes: b6a2fea39318 ("mm: variable length argument support") Fixes: 5edc2a5123a7 ("binfmt_elf_fdpic: wire up AT_EXECFD, AT_EXECFN, AT_SECURE") Signed-off-by: Max Filippov Link: https://lore.kernel.org/r/20240320182607.1472887-1-jcmvbkbc@gmail.com Signed-off-by: Kees Cook --- fs/exec.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/exec.c b/fs/exec.c index e7d9d6ad980bd7..f666398205800a 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -895,6 +895,7 @@ int transfer_args_to_stack(struct linux_binprm *bprm, goto out; } + bprm->exec += *sp_location - MAX_ARG_PAGES * PAGE_SIZE; *sp_location = sp; out: -- cgit 1.2.3-korg