SeaBIOS implements the SMBIOS 2.1 entry point which is limited to a
maximum length of 0xffff. If the SMBIOS data received from QEMU is large
enough, then adding the type 0 table will cause integer overflow. This
results in fun behaviour such as a KVM crash, or hangs in SeaBIOS.
Signed-off-by: Daniel P. Berrangé <berra...@redhat.com>
---
src/fw/biostables.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/src/fw/biostables.c b/src/fw/biostables.c
index 0c07833..794b5be 100644
--- a/src/fw/biostables.c
+++ b/src/fw/biostables.c
@@ -462,10 +462,16 @@ smbios_romfile_setup(void)
/* common case: add our own type 0, with 3 strings and 4 '\0's */
u16 t0_len = sizeof(struct smbios_type_0) + strlen(BIOS_NAME) +
strlen(VERSION) + strlen(BIOS_DATE) + 4;
- ep.structure_table_length += t0_len;
- if (t0_len > ep.max_structure_size)
- ep.max_structure_size = t0_len;
- ep.number_of_structures++;
+ if (t0_len > (0xffff - ep.structure_table_length)) {
+ dprintf(1, "Insufficient space (%d bytes) to add SMBIOS type 0
table (%d bytes)\n",
+ 0xffff - ep.structure_table_length, t0_len);
+ need_t0 = 0;
+ } else {
+ ep.structure_table_length += t0_len;
+ if (t0_len > ep.max_structure_size)
+ ep.max_structure_size = t0_len;
+ ep.number_of_structures++;
+ }
}
/* allocate final blob and record its address in the entry point */
--
2.26.2
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