From: Alec Brown Date: Mon, 22 May 2023 20:52:48 +0000 (-0400) Subject: loader/multiboot_elfxx: Check program header offset doesn't exceed constraints X-Git-Tag: grub-2.12-rc1~59 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=78bc9a9b2bd812c32a0f9773d30a5ed46ba568a5;p=thirdparty%2Fgrub.git loader/multiboot_elfxx: Check program header offset doesn't exceed constraints In grub-core/loader/multiboot_elfxx.c, we need to make sure that the program header offset is less than the file size along with the MULTIBOOT_SEARCH constant. We can do so by setting the variable phlimit to the minimum value of the two limits and check it each time we change program header index to insure that the program header offset isn't outside of the limits. Fixes: CID 314029 Fixes: CID 314038 Signed-off-by: Alec Brown Reviewed-by: Daniel Kiper --- diff --git a/grub-core/loader/multiboot_elfxx.c b/grub-core/loader/multiboot_elfxx.c index a81a8d38b..1edad0594 100644 --- a/grub-core/loader/multiboot_elfxx.c +++ b/grub-core/loader/multiboot_elfxx.c @@ -70,6 +70,7 @@ CONCAT(grub_multiboot_load_elf, XX) (mbi_load_data_t *mld) grub_uint32_t load_offset = 0, load_size = 0; Elf_Shnum shnum; Elf_Word shstrndx, phnum; + grub_off_t phlimit; unsigned int i; void *source = NULL; @@ -100,7 +101,8 @@ CONCAT(grub_multiboot_load_elf, XX) (mbi_load_data_t *mld) return err; /* FIXME: Should we support program headers at strange locations? */ - if (ehdr->e_phoff + phnum * ehdr->e_phentsize > MULTIBOOT_SEARCH) + phlimit = grub_min (MULTIBOOT_SEARCH, grub_file_size (mld->file)); + if ((grub_off_t) ehdr->e_phoff + phnum * ehdr->e_phentsize > phlimit) return grub_error (GRUB_ERR_BAD_OS, "program header at a too high offset"); phdr_base = (char *) mld->buffer + ehdr->e_phoff;