build-id: require program headers to be right after ELF header

Neither ELF spec not ELF loader require program header to be placed right
after ELF header, but build-id code very much assumes such placement:

See

	find_get_page(vma->vm_file->f_mapping, 0);

line and checks against PAGE_SIZE.

Returns errors for now until someone rewrites build-id parser
to be more inline with load_elf_binary().

Link: https://lkml.kernel.org/r/d58bc281-6ca7-467a-9a64-40fa214bd63e@p183
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/lib/buildid.c b/lib/buildid.c
index 7954dd92e36c0137775562c28caebfb1b5b88d10..e02b5507418b40476ebdddae38ec1ae2208dea3a 100644 (file)
--- a/lib/buildid.c
+++ b/lib/buildid.c
@@ -73,6 +73,13 @@ static int get_build_id_32(const void *page_addr, unsigned char *build_id,
        Elf32_Phdr *phdr;
        int i;
 
+       /*
+        * FIXME
+        * Neither ELF spec nor ELF loader require that program headers
+        * start immediately after ELF header.
+        */
+       if (ehdr->e_phoff != sizeof(Elf32_Ehdr))
+               return -EINVAL;
        /* only supports phdr that fits in one page */
        if (ehdr->e_phnum >
            (PAGE_SIZE - sizeof(Elf32_Ehdr)) / sizeof(Elf32_Phdr))
@@ -98,6 +105,13 @@ static int get_build_id_64(const void *page_addr, unsigned char *build_id,
        Elf64_Phdr *phdr;
        int i;
 
+       /*
+        * FIXME
+        * Neither ELF spec nor ELF loader require that program headers
+        * start immediately after ELF header.
+        */
+       if (ehdr->e_phoff != sizeof(Elf64_Ehdr))
+               return -EINVAL;
        /* only supports phdr that fits in one page */
        if (ehdr->e_phnum >
            (PAGE_SIZE - sizeof(Elf64_Ehdr)) / sizeof(Elf64_Phdr))