From 8daf801f6bd29a709e263fb6d3f9a9b8e918c8e7 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Fri, 7 Nov 2014 12:59:08 -0500 Subject: [PATCH 05/10] hw/arm/boot: pass an address limit to and return size from load_dtb() Message-id: <1415383153-28089-6-git-send-email-wei@redhat.com> Patchwork-id: 62215 O-Subject: RHELSA qemu-kvm-rhev PATCH 05/10] hw/arm/boot: pass an address limit to and return size from load_dtb() Bugzilla: 1160325 RH-Acked-by: Andrew Jones Add an address limit input parameter to load_dtb() so that we can tell load_dtb() how much memory the dtb is allowed to consume. If the dtb doesn't fit, return 0, otherwise return the actual size of the loaded dtb. Reviewed-by: Peter Maydell Signed-off-by: Ard Biesheuvel Message-id: 1410453915-9344-3-git-send-email-ard.biesheuvel@linaro.org Signed-off-by: Peter Maydell Signed-off-by: Wei Huang --- hw/arm/boot.c | 34 +++++++++++++++++++++++++++++++--- 1 file changed, 31 insertions(+), 3 deletions(-) diff --git a/hw/arm/boot.c b/hw/arm/boot.c index 668920a..f0e834b 100644 --- a/hw/arm/boot.c +++ b/hw/arm/boot.c @@ -312,7 +312,26 @@ static void set_kernel_args_old(const struct arm_boot_info *info) } } -static int load_dtb(hwaddr addr, const struct arm_boot_info *binfo) +/** + * load_dtb() - load a device tree binary image into memory + * @addr: the address to load the image at + * @binfo: struct describing the boot environment + * @addr_limit: upper limit of the available memory area at @addr + * + * Load a device tree supplied by the machine or by the user with the + * '-dtb' command line option, and put it at offset @addr in target + * memory. + * + * If @addr_limit contains a meaningful value (i.e., it is strictly greater + * than @addr), the device tree is only loaded if its size does not exceed + * the limit. + * + * Returns: the size of the device tree image on success, + * 0 if the image size exceeds the limit, + * -1 on errors. + */ +static int load_dtb(hwaddr addr, const struct arm_boot_info *binfo, + hwaddr addr_limit) { void *fdt = NULL; int size, rc; @@ -341,6 +360,15 @@ static int load_dtb(hwaddr addr, const struct arm_boot_info *binfo) } } + if (addr_limit > addr && size > (addr_limit - addr)) { + /* Installing the device tree blob at addr would exceed addr_limit. + * Whether this constitutes failure is up to the caller to decide, + * so just return 0 as size, i.e., no error. + */ + g_free(fdt); + return 0; + } + acells = qemu_fdt_getprop_cell(fdt, "/", "#address-cells"); scells = qemu_fdt_getprop_cell(fdt, "/", "#size-cells"); if (acells == 0 || scells == 0) { @@ -403,7 +431,7 @@ static int load_dtb(hwaddr addr, const struct arm_boot_info *binfo) g_free(fdt); - return 0; + return size; fail: g_free(fdt); @@ -561,7 +589,7 @@ void arm_load_kernel(ARMCPU *cpu, struct arm_boot_info *info) */ hwaddr dtb_start = QEMU_ALIGN_UP(info->initrd_start + initrd_size, 4096); - if (load_dtb(dtb_start, info)) { + if (load_dtb(dtb_start, info, 0) < 0) { exit(1); } fixupcontext[FIXUP_ARGPTR] = dtb_start; -- 1.8.3.1