From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 From: Daniel Axtens Date: Tue, 8 Mar 2022 23:47:46 +1100 Subject: [PATCH] net/netbuff: Block overly large netbuff allocs A netbuff shouldn't be too huge. It's bounded by MTU and TCP segment reassembly. This helps avoid some bugs (and provides a spot to instrument to catch them at their source). Signed-off-by: Daniel Axtens Reviewed-by: Daniel Kiper (cherry picked from commit ee9591103004cd13b4efadda671536090ca7fd57) (cherry picked from commit acde668bb9d9fa862a1a63e3bbd5fa47fdfa9183) (cherry picked from commit e47ad2eb4fe38ef2bdcab52245286f31170e73e3) --- grub-core/net/netbuff.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/grub-core/net/netbuff.c b/grub-core/net/netbuff.c index dbeeefe478..d5e9e9a0d7 100644 --- a/grub-core/net/netbuff.c +++ b/grub-core/net/netbuff.c @@ -79,10 +79,23 @@ grub_netbuff_alloc (grub_size_t len) COMPILE_TIME_ASSERT (NETBUFF_ALIGN % sizeof (grub_properly_aligned_t) == 0); + /* + * The largest size of a TCP packet is 64 KiB, and everything else + * should be a lot smaller - most MTUs are 1500 or less. Cap data + * size at 64 KiB + a buffer. + */ + if (len > 0xffffUL + 0x1000UL) + { + grub_error (GRUB_ERR_BUG, + "attempted to allocate a packet that is too big"); + return NULL; + } + if (len < NETBUFFMINLEN) len = NETBUFFMINLEN; len = ALIGN_UP (len, NETBUFF_ALIGN); + #ifdef GRUB_MACHINE_EMU data = grub_malloc (len + sizeof (*nb)); #else