| Message ID | 485715E6BEC61FE5+20250317052325.24365-2-chenlinxuan@deepin.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [stable,6.6,v3] lib/buildid: Handle memfd_secret() files in build_id_parse() | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Guessing tree name failed - patch did not apply |
On Mon, Mar 17, 2025 at 01:23:25PM +0800, Chen Linxuan wrote: > [ Upstream commit 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: Yi Lai <yi1.lai@intel.com> > Suggested-by: Shakeel Butt <shakeel.butt@linux.dev> > Signed-off-by: Andrii Nakryiko <andrii@kernel.org> > Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> > Acked-by: Shakeel 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 > [ Chen Linxuan: backport same logic without folio-based changes ] > Cc: stable@vger.kernel.org > Fixes: 88a16a130933 ("perf: Add build id data in mmap2 event") > Signed-off-by: Chen Linxuan <chenlinxuan@deepin.org> lgtm Reviewed-by: Jiri Olsa <jolsa@kernel.org> jirka > --- > v1 -> v2: use vma_is_secretmem() instead of directly checking > vma->vm_file->f_op == &secretmem_fops > v2 -> v3: keep original comment > --- > lib/buildid.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/lib/buildid.c b/lib/buildid.c > index 9fc46366597e..8d839ff5548e 100644 > --- a/lib/buildid.c > +++ b/lib/buildid.c > @@ -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 (vma_is_secretmem(vma)) > + return -EFAULT; > + > page = find_get_page(vma->vm_file->f_mapping, 0); > if (!page) > return -EFAULT; /* page not mapped */ > -- > 2.48.1 > >
diff --git a/lib/buildid.c b/lib/buildid.c index 9fc46366597e..8d839ff5548e 100644 --- a/lib/buildid.c +++ b/lib/buildid.c @@ -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 (vma_is_secretmem(vma)) + return -EFAULT; + page = find_get_page(vma->vm_file->f_mapping, 0); if (!page) return -EFAULT; /* page not mapped */