From 34b47764297130b21aaeb4cc6119bb811814b8e3 Mon Sep 17 00:00:00 2001 From: WANG Chao Date: Tue, 17 Feb 2015 13:46:01 -0800 Subject: [PATCH] vmcore: fix PT_NOTE n_namesz, n_descsz overflow issue When updating PT_NOTE header size (ie. p_memsz), an overflow issue happens with the following bogus note entry: n_namesz = 0xFFFFFFFF n_descsz = 0x0 n_type = 0x0 This kind of note entry should be dropped during updating p_memsz. But because n_namesz is 32bit, after (n_namesz + 3) & (~3), it's overflow to 0x0, the note entry size looks sane and reserved. When userspace (eg. crash utility) is trying to access such bogus note, it could lead to an unexpected behavior (eg. crash utility segment fault because it's reading bogus address). The source of bogus note hasn't been identified yet. At least we could drop the bogus note so user space wouldn't be surprised. Signed-off-by: WANG Chao Cc: Dave Anderson Cc: Baoquan He Cc: Randy Wright Cc: Vivek Goyal Cc: Paul Gortmaker Cc: Fabian Frederick Cc: Vitaly Kuznetsov Cc: Rashika Kheria Cc: Greg Pearson Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/proc/vmcore.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c index a90d6d354199..4e61388ec03d 100644 --- a/fs/proc/vmcore.c +++ b/fs/proc/vmcore.c @@ -546,8 +546,8 @@ static int __init update_note_header_size_elf64(const Elf64_Ehdr *ehdr_ptr) nhdr_ptr = notes_section; while (nhdr_ptr->n_namesz != 0) { sz = sizeof(Elf64_Nhdr) + - ((nhdr_ptr->n_namesz + 3) & ~3) + - ((nhdr_ptr->n_descsz + 3) & ~3); + (((u64)nhdr_ptr->n_namesz + 3) & ~3) + + (((u64)nhdr_ptr->n_descsz + 3) & ~3); if ((real_sz + sz) > max_sz) { pr_warn("Warning: Exceeded p_memsz, dropping PT_NOTE entry n_namesz=0x%x, n_descsz=0x%x\n", nhdr_ptr->n_namesz, nhdr_ptr->n_descsz); @@ -732,8 +732,8 @@ static int __init update_note_header_size_elf32(const Elf32_Ehdr *ehdr_ptr) nhdr_ptr = notes_section; while (nhdr_ptr->n_namesz != 0) { sz = sizeof(Elf32_Nhdr) + - ((nhdr_ptr->n_namesz + 3) & ~3) + - ((nhdr_ptr->n_descsz + 3) & ~3); + (((u64)nhdr_ptr->n_namesz + 3) & ~3) + + (((u64)nhdr_ptr->n_descsz + 3) & ~3); if ((real_sz + sz) > max_sz) { pr_warn("Warning: Exceeded p_memsz, dropping PT_NOTE entry n_namesz=0x%x, n_descsz=0x%x\n", nhdr_ptr->n_namesz, nhdr_ptr->n_descsz); -- 2.34.1