Re: [ 11/83] module: fix out-by-one error in kallsyms
From: Rusty Russell <hidden>
Date: 2012-12-03 02:44:44
Also in:
lkml
Subsystem:
the rest · Maintainer:
Linus Torvalds
satoru takeuchi [off-list ref] writes:
Hi,
Hi!
quoted
--- a/kernel/module.c +++ b/kernel/module.c@@ -2273,12 +2273,17 @@ static void layout_symtab(struct module src = (void *)info->hdr + symsect->sh_offset; nsrc = symsect->sh_size / sizeof(*src); + /* strtab always starts with a nul, so offset 0 is the empty string. */ + strtab_size = 1; +I suspect above code sniped is not needed since the size of src[0](always 1) is counted at the following code("strtab_size += strlen(..) + 1;").
You are correct, on both counts. This was a remnant of the previous 1-based looping. Here's the fix I have pending. Thanks! Rusty. module: fix one byte kallsyms overallocation. Since we fixed our kallsyms strtab expansion code in 59ef28b1f14899b10d6b2682c7057ca00a9a3f47 (module: fix out-by-one error in kallsyms) we now loop from zero, so we don't need to add an extra byte for the first empty string. Reported-by: satoru takeuchi <redacted> Signed-off-by: Rusty Russell <redacted>
diff --git a/kernel/module.c b/kernel/module.c
index a1d2ed8..79a526d 100644
--- a/kernel/module.c
+++ b/kernel/module.c@@ -2285,7 +2285,7 @@ static void layout_symtab(struct module *mod, struct load_info *info) Elf_Shdr *symsect = info->sechdrs + info->index.sym; Elf_Shdr *strsect = info->sechdrs + info->index.str; const Elf_Sym *src; - unsigned int i, nsrc, ndst, strtab_size; + unsigned int i, nsrc, ndst, strtab_size = 0; /* Put symbol section at end of init part of module. */ symsect->sh_flags |= SHF_ALLOC;
@@ -2296,9 +2296,6 @@ static void layout_symtab(struct module *mod, struct load_info *info) src = (void *)info->hdr + symsect->sh_offset; nsrc = symsect->sh_size / sizeof(*src); - /* strtab always starts with a nul, so offset 0 is the empty string. */ - strtab_size = 1; - /* Compute total space required for the core symbols' strtab. */ for (ndst = i = 0; i < nsrc; i++) { if (i == 0 ||
@@ -2340,7 +2337,6 @@ static void add_kallsyms(struct module *mod, const struct load_info *info) mod->core_symtab = dst = mod->module_core + info->symoffs; mod->core_strtab = s = mod->module_core + info->stroffs; src = mod->symtab; - *s++ = 0; for (ndst = i = 0; i < mod->num_symtab; i++) { if (i == 0 || is_core_symbol(src+i, info->sechdrs, info->hdr->e_shnum)) {