In the Linux kernel, the following vulnerability has been resolved:
bootconfig: Fix integer overflow in initrd size check
Sashiko reported that in get_boot_config_from_initrd(), a crafted initrd
with a huge bootconfig size (such as 0xFFFFFFFF) can cause the pointer
arithmetic:
data = ((void *)hdr) – size;
to wrap around on 32-bit systems (or when pointer subtraction overflows).
Because data wraps around, the subsequent bounds check:
if ((unsigned long)data 4.29 GB, an
unbounded 32-bit size can similarly bypass the initrd_start check.
Fix this by:
1. Ensuring the initrd is at least large enough to contain the bootconfig
footer and verifying hdr is within the initrd bounds.
2. Checking that size does not exceed XBC_DATA_MAX and does not exceed
the available space between initrd_start and hdr before performing
pointer subtraction.
