Greg KH <greg@xxxxxxxxx> 于2025年3月17日周一 12:20写道： > > On Mon, Mar 17, 2025 at 09:16:04AM +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@xxxxxxxxx> > > Suggested-by: Shakeel Butt <shakeel.butt@xxxxxxxxx> > > Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx> > > Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx> > > Acked-by: Shakeel Butt <shakeel.butt@xxxxxxxxx> > > Link: https://lore.kernel.org/bpf/20241017175431.6183-A-hca@xxxxxxxxxxxxx > > Link: https://lore.kernel.org/bpf/20241017174713.2157873-1-andrii@xxxxxxxxxx > > [ Chen Linxuan: backport same logic without folio-based changes ] > > Cc: stable@xxxxxxxxxxxxxxx > > Fixes: 88a16a130933 ("perf: Add build id data in mmap2 event") > > Signed-off-by: Chen Linxuan <chenlinxuan@xxxxxxxxxx> > > --- > > v1 -> v2: use vma_is_secretmem() instead of directly checking > > vma->vm_file->f_op == &secretmem_fops > > --- > > lib/buildid.c | 5 +++++ > > 1 file changed, 5 insertions(+) > > > > diff --git a/lib/buildid.c b/lib/buildid.c > > index 9fc46366597e..34315d09b544 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 */ > > Why is this comment different from what is in the original commit? Same > for your other backports. Please try to keep it as identical to the > original whenever possible as we have to maintain this for a very long > time. > > thanks, > > greg k-h > > Original comment is in a function named freader_get_folio(), but folio related changes has not been backported yet. thanks, Chen Linxuan
