Re: regression: crash from 'ls /sys/modules/wl1251_spi/notes'

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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 =&sect_attrs->attrs[0];
  	gattr =&sect_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 =&notes_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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