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Date: Thu, 31 Dec 2009 22:15:08 +0100
From: Helge Deller <deller@....de>
To: James Bottomley <James.Bottomley@...senPartnership.com>,
ben@...adent.org.uk, tbm@...ius.com
CC: Kalle Valo <kalle.valo@....fi>, linux-kernel@...r.kernel.org,
linux-wireless@...r.kernel.org, linux-omap@...r.kernel.org,
rusty@...tcorp.com.au, akpm@...ux-foundation.org,
roland@...hat.com, dave@...uly1.hia.nrc.ca,
Parisc List <linux-parisc@...r.kernel.org>
Subject: Re: regression: crash from 'ls /sys/modules/wl1251_spi/notes'
On 12/30/2009 04:49 PM, James Bottomley wrote:
> A better, and more comprehensive patch would be to try not to count the
> empty text sections when we're building the notes section (and actually
> anywhere else in the file). This patch actually relies on the fact that
> if sh_size is zero for the text section it should be for the
> corresponding notes section. If that doesn't work, we'd actually have
> to do the matching in the construction piece.
>
> Can you try it to see if it works for you? If it doesn't, I'll try
> matching notes to text. It works fine on parisc, but as we don't have a
> notes section, that's not saying much ...
>
> Thanks,
>
> James
Ben Hutchings already sent a similar patch.
See: http://patchwork.kernel.org/patch/68925/
IMHO James patch below seems better since it
checks if a section will be allocated at a few more
places...
Helge
> ---
>
> diff --git a/kernel/module.c b/kernel/module.c
> index e96b8ed..957f912 100644
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -132,6 +132,11 @@ void __module_put_and_exit(struct module *mod, long code)
> }
> EXPORT_SYMBOL(__module_put_and_exit);
>
> +static inline int section_allocated(Elf_Shdr hdr)
> +{
> + return (hdr.sh_flags& SHF_ALLOC)&& hdr.sh_size != 0;
> +}
> +
> /* Find a module section: 0 means not found. */
> static unsigned int find_sec(Elf_Ehdr *hdr,
> Elf_Shdr *sechdrs,
> @@ -142,7 +147,7 @@ static unsigned int find_sec(Elf_Ehdr *hdr,
>
> for (i = 1; i< hdr->e_shnum; i++)
> /* Alloc bit cleared means "ignore it." */
> - if ((sechdrs[i].sh_flags& SHF_ALLOC)
> + if (section_allocated(sechdrs[i])
> && strcmp(secstrings+sechdrs[i].sh_name, name) == 0)
> return i;
> return 0;
> @@ -1051,8 +1056,7 @@ static void add_sect_attrs(struct module *mod, unsigned int nsect,
>
> /* Count loaded sections and allocate structures */
> for (i = 0; i< nsect; i++)
> - if (sechdrs[i].sh_flags& SHF_ALLOC
> - && sechdrs[i].sh_size)
> + if (section_allocated(sechdrs[i]))
> nloaded++;
> size[0] = ALIGN(sizeof(*sect_attrs)
> + nloaded * sizeof(sect_attrs->attrs[0]),
> @@ -1070,9 +1074,7 @@ static void add_sect_attrs(struct module *mod, unsigned int nsect,
> sattr =§_attrs->attrs[0];
> gattr =§_attrs->grp.attrs[0];
> for (i = 0; i< nsect; i++) {
> - if (! (sechdrs[i].sh_flags& SHF_ALLOC))
> - continue;
> - if (!sechdrs[i].sh_size)
> + if (!section_allocated(sechdrs[i]))
> continue;
> sattr->address = sechdrs[i].sh_addr;
> sattr->name = kstrdup(secstrings + sechdrs[i].sh_name,
> @@ -1156,7 +1158,7 @@ static void add_notes_attrs(struct module *mod, unsigned int nsect,
> /* Count notes sections and allocate structures. */
> notes = 0;
> for (i = 0; i< nsect; i++)
> - if ((sechdrs[i].sh_flags& SHF_ALLOC)&&
> + if (section_allocated(sechdrs[i])&&
> (sechdrs[i].sh_type == SHT_NOTE))
> ++notes;
>
> @@ -1172,7 +1174,7 @@ static void add_notes_attrs(struct module *mod, unsigned int nsect,
> notes_attrs->notes = notes;
> nattr =¬es_attrs->attrs[0];
> for (loaded = i = 0; i< nsect; ++i) {
> - if (!(sechdrs[i].sh_flags& SHF_ALLOC))
> + if (!section_allocated(sechdrs[i]))
> continue;
> if (sechdrs[i].sh_type == SHT_NOTE) {
> nattr->attr.name = mod->sect_attrs->attrs[loaded].name;
> @@ -1720,7 +1722,7 @@ static char elf_type(const Elf_Sym *sym,
> return '?';
> if (sechdrs[sym->st_shndx].sh_flags& SHF_EXECINSTR)
> return 't';
> - if (sechdrs[sym->st_shndx].sh_flags& SHF_ALLOC
> + if (section_allocated(sechdrs[sym->st_shndx])
> && sechdrs[sym->st_shndx].sh_type != SHT_NOBITS) {
> if (!(sechdrs[sym->st_shndx].sh_flags& SHF_WRITE))
> return 'r';
> @@ -1751,7 +1753,7 @@ static bool is_core_symbol(const Elf_Sym *src, const Elf_Shdr *sechdrs,
> return false;
>
> sec = sechdrs + src->st_shndx;
> - if (!(sec->sh_flags& SHF_ALLOC)
> + if (!section_allocated(*sec)
> #ifndef CONFIG_KALLSYMS_ALL
> || !(sec->sh_flags& SHF_EXECINSTR)
> #endif
> @@ -1913,7 +1915,7 @@ static void kmemleak_load_module(struct module *mod, Elf_Ehdr *hdr,
> kmemleak_scan_area(mod, sizeof(struct module), GFP_KERNEL);
>
> for (i = 1; i< hdr->e_shnum; i++) {
> - if (!(sechdrs[i].sh_flags& SHF_ALLOC))
> + if (!section_allocated(sechdrs[i]))
> continue;
> if (strncmp(secstrings + sechdrs[i].sh_name, ".data", 5) != 0
> && strncmp(secstrings + sechdrs[i].sh_name, ".bss", 4) != 0)
> @@ -2139,7 +2141,7 @@ static noinline struct module *load_module(void __user *umod,
> for (i = 0; i< hdr->e_shnum; i++) {
> void *dest;
>
> - if (!(sechdrs[i].sh_flags& SHF_ALLOC))
> + if (!section_allocated(sechdrs[i]))
> continue;
>
> if (sechdrs[i].sh_entsize& INIT_OFFSET_MASK)
> @@ -2287,7 +2289,7 @@ static noinline struct module *load_module(void __user *umod,
> continue;
>
> /* Don't bother with non-allocated sections */
> - if (!(sechdrs[info].sh_flags& SHF_ALLOC))
> + if (!section_allocated(sechdrs[info]))
> continue;
>
> if (sechdrs[i].sh_type == SHT_REL)
>
>
--
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