Commit bf228259 authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Tong Tiangen
Browse files

lib/buildid: Handle memfd_secret() files in build_id_parse() 

mainline inclusion
from mainline-v6.12-rc4
commit 5ac9b4e935dfc6af41eee2ddc21deb5c36507a9f
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/IBJ8HQ

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=5ac9b4e935dfc6af41eee2ddc21deb5c36507a9f

--------------------------------

>From memfd_secret(2) manpage:

  The memory areas backing the file created with memfd_secret(2) are
  visible only to the processes that have access to the file descriptor.
  The memory region is removed from the kernel page tables and only the
  page tables of the processes holding the file descriptor map the
  corresponding physical memory. (Thus, the pages in the region can't be
  accessed by the kernel itself, so that, for example, pointers to the
  region can't be passed to system calls.)

We need to handle this special case gracefully in build ID fetching
code. Return -EFAULT whenever secretmem file is passed to build_id_parse()
family of APIs. Original report and repro can be found in [0].

  [0] https://lore.kernel.org/bpf/ZwyG8Uro%2FSyTXAni@ly-workstation/



Fixes: de3ec364c3c3 ("lib/buildid: add single folio-based file reader abstraction")
Reported-by: default avatarYi Lai <yi1.lai@intel.com>
Suggested-by: default avatarShakeel Butt <shakeel.butt@linux.dev>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarShakeel Butt <shakeel.butt@linux.dev>
Link: https://lore.kernel.org/bpf/20241017175431.6183-A-hca@linux.ibm.com
Link: https://lore.kernel.org/bpf/20241017174713.2157873-1-andrii@kernel.org


Conflicts:
	lib/buildid.c
[ Pre-patch de3ec364c3c3 not merge ]
Signed-off-by: default avatarTong Tiangen <tongtiangen@huawei.com>
parent 40baf156

lib/buildid.c

+5 −0
Original line number Diff line number Diff line
@@ -5,6 +5,7 @@ 
#include <linux/elf.h>

#include <linux/kernel.h>

#include <linux/pagemap.h>

#include <linux/secretmem.h>



#define BUILD_ID 3
@@ -157,6 +158,10 @@ int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id, 
	if (!vma->vm_file)

		return -EINVAL;



	/* reject secretmem folios created with memfd_secret() */

	if (secretmem_mapping(vma->vm_file->f_mapping))

		return -EFAULT;



	page = find_get_page(vma->vm_file->f_mapping, 0);

	if (!page)

		return -EFAULT;	/* page not mapped */