Backport of a similar change from commit 5ac9b4e935df ("lib/buildid:
Handle memfd_secret() files in build_id_parse()") to address an issue
where accessing secret memfd contents through build_id_parse() would
trigger faults.
Original report and repro can be found in [0].
[0] https://lore.kernel.org/bpf/ZwyG8Uro%2FSyTXAni@ly-workstation/
This repro will cause BUG: unable to handle kernel paging request in
build_id_parse in 5.15/6.1/6.6.
Some other discussions can be found in [1].
[1] https://lore.kernel.org/bpf/20241104175256.2327164-1-jolsa@xxxxxxxxxx/T/#u
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 88a16a130933 ("perf: Add build id data in mmap2 event")
Signed-off-by: Chen Linxuan <chenlinxuan@xxxxxxxxxx>
---
lib/buildid.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/lib/buildid.c b/lib/buildid.c
index 9fc46366597e..b78d119ed1f7 100644
--- a/lib/buildid.c
+++ b/lib/buildid.c
@@ -157,6 +157,12 @@ int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id,
if (!vma->vm_file)
return -EINVAL;
+#ifdef CONFIG_SECRETMEM
+ /* reject secretmem folios created with memfd_secret() */
+ if (vma->vm_file->f_mapping->a_ops == &secretmem_aops)
+ return -EFAULT;
+#endif
+
page = find_get_page(vma->vm_file->f_mapping, 0);
if (!page)
return -EFAULT; /* page not mapped */
--
2.48.1
