[PATCH] diskfilter: don't make a RAID array with more than 1024 disks

[Daniel Axtens]

This is 'belt and braces' with commit 12e20a6a695f ("disk/diskfilter:
Check calloc() result for NULL"): we end up trying to use too much memory
in situations like corrupted Linux software raid setups purporting to
use a huge number of disks. Simply refuse to permit such configurations.

1024 is a bit arbitrary, yes, and I feel a bit like I'm tempting fate
here, but I think 1024 disks in an array (that grub has to read to boot!)
should be enough for anyone.

Signed-off-by: Daniel Axtens <dja@axtens.net>

---

v2: add a minimum of 1 disk as nmemb is a signed integer.

Tested with `./grub-fs-tester` using mdraid12_raid1 and mdraid12_raid5.
Hopefully that means things work; I don't have software raid set up locally.
---
 grub-core/disk/diskfilter.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/grub-core/disk/diskfilter.c b/grub-core/disk/diskfilter.c
index 4ac50320ef4e..24de8e6c6521 100644
--- a/grub-core/disk/diskfilter.c
+++ b/grub-core/disk/diskfilter.c
@@ -1046,6 +1046,13 @@ grub_diskfilter_make_raid (grub_size_t uuidlen, char 
*uuid, int nmemb,
   struct grub_diskfilter_pv *pv;
   grub_err_t err;
 
+  /* We choose not to support more than 1024 disks */
+  if (nmemb < 1 || nmemb > 1024)
+    {
+      grub_free (uuid);
+      return NULL;
+    }
+
   switch (level)
     {
     case 1:
-- 
2.25.1