5.4-stable review patch. If anyone has any objections, please let me know.
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From: Max Filippov jcmvbkbc@gmail.com
commit 2aea94ac14d1e0a8ae9e34febebe208213ba72f7 upstream.
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: stable@vger.kernel.org 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 jcmvbkbc@gmail.com Link: https://lore.kernel.org/r/20240320182607.1472887-1-jcmvbkbc@gmail.com Signed-off-by: Kees Cook keescook@chromium.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/exec.c | 1 + 1 file changed, 1 insertion(+)
--- a/fs/exec.c +++ b/fs/exec.c @@ -836,6 +836,7 @@ int transfer_args_to_stack(struct linux_ goto out; }
+ bprm->exec += *sp_location - MAX_ARG_PAGES * PAGE_SIZE; *sp_location = sp;
out: