If a DMI table entry is shorter than 4 bytes, it is invalid. Due to
how DMI table parsing works, it is impossible to safely recover from
such an error, so we have to stop decoding the table.
Signed-off-by: Jean Delvare <jdelvare@suse.de>
Link: https://lore.kernel.org/linux-kernel/Zh2K3-HLXOesT_vZ@liuwe-devbox-debian-v2/T/
---
Michael, can you please test this patch and confirm that it prevents
the early oops?
The root cause of the DMI table corruption still needs to be
investigated.
drivers/firmware/dmi_scan.c | 11 +++++++++++
1 file changed, 11 insertions(+)
--- linux-6.8.orig/drivers/firmware/dmi_scan.c
+++ linux-6.8/drivers/firmware/dmi_scan.c
@@ -102,6 +102,17 @@ static void dmi_decode_table(u8 *buf,
const struct dmi_header *dm = (const struct dmi_header *)data;
/*
+ * If a short entry is found (less than 4 bytes), not only it
+ * is invalid, but we cannot reliably locate the next entry.
+ */
+ if (dm->length < sizeof(struct dmi_header)) {
+ pr_warn(FW_BUG
+ "Corrupted DMI table (only %d entries processed)\n",
+ i);
+ break;
+ }
+
+ /*
* We want to know the total length (formatted area and
* strings) before decoding to make sure we won't run off the
* table in dmi_decode or dmi_string
--
Jean Delvare
SUSE L3 Support