From 23daab14a66d407db4ea81811bddf9da95cc35e9 Mon Sep 17 00:00:00 2001 From: Michael Brown Date: Tue, 15 Mar 2011 01:52:58 +0000 Subject: [PATCH] [romprefix] Use correct size for PMM allocation of image source block iPXE allocates its first PMM block using the image source length, which is rounded up to the nearest 16-byte paragraph. It then copies in data of a length calculated from the ROM size, which is theoretically less than or equal to the image source length, but is rounded up to the nearest 512-byte sector. This can result in copying beyond the end of the allocated PMM block, which can corrupt the PMM data structures (and other essentially arbitrary areas of memory). Fix by rounding up the image source length to the nearest 512-byte sector before using it as the PMM allocation length. Reported-by: Alex Williamson Reported-by: Jarrod Johnson Reported-by: Itay Gazit Signed-off-by: Michael Brown --- src/arch/i386/prefix/romprefix.S | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/src/arch/i386/prefix/romprefix.S b/src/arch/i386/prefix/romprefix.S index ede0fb425..dd602ddb7 100644 --- a/src/arch/i386/prefix/romprefix.S +++ b/src/arch/i386/prefix/romprefix.S @@ -320,7 +320,8 @@ pmm_scan: /* We have PMM and so a 1kB stack: preserve whole registers */ pushal /* Allocate image source PMM block */ - movzwl image_source_len_pgh, %ecx + movzwl image_source_size, %ecx + shll $5, %ecx movl $PMM_HANDLE_BASE_IMAGE_SOURCE, %ebx movw $get_pmm_image_source, %bp call get_pmm @@ -565,16 +566,16 @@ image_source: .long 0 .size image_source, . - image_source -/* Image source area length (in paragraphs) +/* Image source size (in 512-byte sectors) * */ -image_source_len_pgh: +image_source_size: .word 0 - .size image_source_len_pgh, . - image_source_len_pgh + .size image_source_size, . - image_source_size .section ".zinfo.fixup", "a", @progbits /* Compressor fixups */ .ascii "ADDW" - .long image_source_len_pgh - .long 16 + .long image_source_size + .long 512 .long 0 .previous