elf coredump: add extended numbering support
The current ELF dumper implementation can produce broken corefiles if
program headers exceed 65535. This number is determined by the number of
vmas which the process have. In particular, some extreme programs may use
more than 65535 vmas. (If you google max_map_count, you can find some
users facing this problem.) This kind of program never be able to generate
correct coredumps.
This patch implements ``extended numbering'' that uses sh_info field of
the first section header instead of e_phnum field in order to represent
upto 4294967295 vmas.
This is supported by
AMD64-ABI(http://www.x86-64.org/documentation.html) and
Solaris(http://docs.sun.com/app/docs/doc/817-1984/).
Of course, we are preparing patches for gdb and binutils.
Signed-off-by: Daisuke HATAYAMA <d.hatayama@jp.fujitsu.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Greg Ungerer <gerg@snapgear.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/ia64/kernel/elfcore.c b/arch/ia64/kernel/elfcore.c
index 57a2298..bac1639 100644
--- a/arch/ia64/kernel/elfcore.c
+++ b/arch/ia64/kernel/elfcore.c
@@ -62,3 +62,19 @@
}
return 1;
}
+
+size_t elf_core_extra_data_size(void)
+{
+ const struct elf_phdr *const gate_phdrs =
+ (const struct elf_phdr *) (GATE_ADDR + GATE_EHDR->e_phoff);
+ int i;
+ size_t size = 0;
+
+ for (i = 0; i < GATE_EHDR->e_phnum; ++i) {
+ if (gate_phdrs[i].p_type == PT_LOAD) {
+ size += PAGE_ALIGN(gate_phdrs[i].p_memsz);
+ break;
+ }
+ }
+ return size;
+}
diff --git a/arch/um/sys-i386/elfcore.c b/arch/um/sys-i386/elfcore.c
index 30cac52..6bb49b6 100644
--- a/arch/um/sys-i386/elfcore.c
+++ b/arch/um/sys-i386/elfcore.c
@@ -65,3 +65,19 @@
}
return 1;
}
+
+size_t elf_core_extra_data_size(void)
+{
+ if ( vsyscall_ehdr ) {
+ const struct elfhdr *const ehdrp =
+ (struct elfhdr *)vsyscall_ehdr;
+ const struct elf_phdr *const phdrp =
+ (const struct elf_phdr *) (vsyscall_ehdr + ehdrp->e_phoff);
+ int i;
+
+ for (i = 0; i < ehdrp->e_phnum; ++i)
+ if (phdrp[i].p_type == PT_LOAD)
+ return (size_t) phdrp[i].p_filesz;
+ }
+ return 0;
+}
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 6fc49b6..78de530 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1838,6 +1838,34 @@
return gate_vma;
}
+static void fill_extnum_info(struct elfhdr *elf, struct elf_shdr *shdr4extnum,
+ elf_addr_t e_shoff, int segs)
+{
+ elf->e_shoff = e_shoff;
+ elf->e_shentsize = sizeof(*shdr4extnum);
+ elf->e_shnum = 1;
+ elf->e_shstrndx = SHN_UNDEF;
+
+ memset(shdr4extnum, 0, sizeof(*shdr4extnum));
+
+ shdr4extnum->sh_type = SHT_NULL;
+ shdr4extnum->sh_size = elf->e_shnum;
+ shdr4extnum->sh_link = elf->e_shstrndx;
+ shdr4extnum->sh_info = segs;
+}
+
+static size_t elf_core_vma_data_size(struct vm_area_struct *gate_vma,
+ unsigned long mm_flags)
+{
+ struct vm_area_struct *vma;
+ size_t size = 0;
+
+ for (vma = first_vma(current, gate_vma); vma != NULL;
+ vma = next_vma(vma, gate_vma))
+ size += vma_dump_size(vma, mm_flags);
+ return size;
+}
+
/*
* Actual dumper
*
@@ -1857,6 +1885,9 @@
unsigned long mm_flags;
struct elf_note_info info;
struct elf_phdr *phdr4note = NULL;
+ struct elf_shdr *shdr4extnum = NULL;
+ Elf_Half e_phnum;
+ elf_addr_t e_shoff;
/*
* We no longer stop all VM operations.
@@ -1885,12 +1916,19 @@
if (gate_vma != NULL)
segs++;
+ /* for notes section */
+ segs++;
+
+ /* If segs > PN_XNUM(0xffff), then e_phnum overflows. To avoid
+ * this, kernel supports extended numbering. Have a look at
+ * include/linux/elf.h for further information. */
+ e_phnum = segs > PN_XNUM ? PN_XNUM : segs;
+
/*
* Collect all the non-memory information about the process for the
* notes. This also sets up the file header.
*/
- if (!fill_note_info(elf, segs + 1, /* including notes section */
- &info, cprm->signr, cprm->regs))
+ if (!fill_note_info(elf, e_phnum, &info, cprm->signr, cprm->regs))
goto cleanup;
has_dumped = 1;
@@ -1900,7 +1938,7 @@
set_fs(KERNEL_DS);
offset += sizeof(*elf); /* Elf header */
- offset += (segs + 1) * sizeof(struct elf_phdr); /* Program headers */
+ offset += segs * sizeof(struct elf_phdr); /* Program headers */
foffset = offset;
/* Write notes phdr entry */
@@ -1926,6 +1964,19 @@
*/
mm_flags = current->mm->flags;
+ offset += elf_core_vma_data_size(gate_vma, mm_flags);
+ offset += elf_core_extra_data_size();
+ e_shoff = offset;
+
+ if (e_phnum == PN_XNUM) {
+ shdr4extnum = kmalloc(sizeof(*shdr4extnum), GFP_KERNEL);
+ if (!shdr4extnum)
+ goto end_coredump;
+ fill_extnum_info(elf, shdr4extnum, e_shoff, segs);
+ }
+
+ offset = dataoff;
+
size += sizeof(*elf);
if (size > cprm->limit || !dump_write(cprm->file, elf, sizeof(*elf)))
goto end_coredump;
@@ -2003,11 +2054,20 @@
if (!elf_core_write_extra_data(cprm->file, &size, cprm->limit))
goto end_coredump;
+ if (e_phnum == PN_XNUM) {
+ size += sizeof(*shdr4extnum);
+ if (size > cprm->limit
+ || !dump_write(cprm->file, shdr4extnum,
+ sizeof(*shdr4extnum)))
+ goto end_coredump;
+ }
+
end_coredump:
set_fs(fs);
cleanup:
free_note_info(&info);
+ kfree(shdr4extnum);
kfree(phdr4note);
kfree(elf);
out:
diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
index 112da49..e49d9c0 100644
--- a/fs/binfmt_elf_fdpic.c
+++ b/fs/binfmt_elf_fdpic.c
@@ -1505,6 +1505,22 @@
return sz;
}
+static void fill_extnum_info(struct elfhdr *elf, struct elf_shdr *shdr4extnum,
+ elf_addr_t e_shoff, int segs)
+{
+ elf->e_shoff = e_shoff;
+ elf->e_shentsize = sizeof(*shdr4extnum);
+ elf->e_shnum = 1;
+ elf->e_shstrndx = SHN_UNDEF;
+
+ memset(shdr4extnum, 0, sizeof(*shdr4extnum));
+
+ shdr4extnum->sh_type = SHT_NULL;
+ shdr4extnum->sh_size = elf->e_shnum;
+ shdr4extnum->sh_link = elf->e_shstrndx;
+ shdr4extnum->sh_info = segs;
+}
+
/*
* dump the segments for an MMU process
*/
@@ -1569,6 +1585,17 @@
}
#endif
+static size_t elf_core_vma_data_size(unsigned long mm_flags)
+{
+ struct vm_area_struct *vma;
+ size_t size = 0;
+
+ for (vma = current->mm->mmap; vma; vma->vm_next)
+ if (maydump(vma, mm_flags))
+ size += vma->vm_end - vma->vm_start;
+ return size;
+}
+
/*
* Actual dumper
*
@@ -1601,6 +1628,9 @@
elf_addr_t *auxv;
unsigned long mm_flags;
struct elf_phdr *phdr4note = NULL;
+ struct elf_shdr *shdr4extnum = NULL;
+ Elf_Half e_phnum;
+ elf_addr_t e_shoff;
/*
* We no longer stop all VM operations.
@@ -1667,8 +1697,16 @@
segs = current->mm->map_count;
segs += elf_core_extra_phdrs();
+ /* for notes section */
+ segs++;
+
+ /* If segs > PN_XNUM(0xffff), then e_phnum overflows. To avoid
+ * this, kernel supports extended numbering. Have a look at
+ * include/linux/elf.h for further information. */
+ e_phnum = segs > PN_XNUM ? PN_XNUM : segs;
+
/* Set up header */
- fill_elf_fdpic_header(elf, segs + 1); /* including notes section */
+ fill_elf_fdpic_header(elf, e_phnum);
has_dumped = 1;
current->flags |= PF_DUMPCORE;
@@ -1708,7 +1746,7 @@
set_fs(KERNEL_DS);
offset += sizeof(*elf); /* Elf header */
- offset += (segs+1) * sizeof(struct elf_phdr); /* Program headers */
+ offset += segs * sizeof(struct elf_phdr); /* Program headers */
foffset = offset;
/* Write notes phdr entry */
@@ -1738,6 +1776,19 @@
*/
mm_flags = current->mm->flags;
+ offset += elf_core_vma_data_size(mm_flags);
+ offset += elf_core_extra_data_size();
+ e_shoff = offset;
+
+ if (e_phnum == PN_XNUM) {
+ shdr4extnum = kmalloc(sizeof(*shdr4extnum), GFP_KERNEL);
+ if (!shdr4extnum)
+ goto end_coredump;
+ fill_extnum_info(elf, shdr4extnum, e_shoff, segs);
+ }
+
+ offset = dataoff;
+
size += sizeof(*elf);
if (size > cprm->limit || !dump_write(cprm->file, elf, sizeof(*elf)))
goto end_coredump;
@@ -1802,6 +1853,14 @@
if (!elf_core_write_extra_data(cprm->file, &size, cprm->limit))
goto end_coredump;
+ if (e_phnum == PN_XNUM) {
+ size += sizeof(*shdr4extnum);
+ if (size > cprm->limit
+ || !dump_write(cprm->file, shdr4extnum,
+ sizeof(*shdr4extnum)))
+ goto end_coredump;
+ }
+
if (cprm->file->f_pos != offset) {
/* Sanity check */
printk(KERN_WARNING
diff --git a/include/linux/elf.h b/include/linux/elf.h
index ccde3fd..5978584 100644
--- a/include/linux/elf.h
+++ b/include/linux/elf.h
@@ -50,6 +50,28 @@
#define PT_GNU_STACK (PT_LOOS + 0x474e551)
+/*
+ * Extended Numbering
+ *
+ * If the real number of program header table entries is larger than
+ * or equal to PN_XNUM(0xffff), it is set to sh_info field of the
+ * section header at index 0, and PN_XNUM is set to e_phnum
+ * field. Otherwise, the section header at index 0 is zero
+ * initialized, if it exists.
+ *
+ * Specifications are available in:
+ *
+ * - Sun microsystems: Linker and Libraries.
+ * Part No: 817-1984-17, September 2008.
+ * URL: http://docs.sun.com/app/docs/doc/817-1984
+ *
+ * - System V ABI AMD64 Architecture Processor Supplement
+ * Draft Version 0.99.,
+ * May 11, 2009.
+ * URL: http://www.x86-64.org/
+ */
+#define PN_XNUM 0xffff
+
/* These constants define the different elf file types */
#define ET_NONE 0
#define ET_REL 1
@@ -286,7 +308,7 @@
#define SHN_COMMON 0xfff2
#define SHN_HIRESERVE 0xffff
-typedef struct {
+typedef struct elf32_shdr {
Elf32_Word sh_name;
Elf32_Word sh_type;
Elf32_Word sh_flags;
@@ -394,6 +416,7 @@
extern Elf32_Dyn _DYNAMIC [];
#define elfhdr elf32_hdr
#define elf_phdr elf32_phdr
+#define elf_shdr elf32_shdr
#define elf_note elf32_note
#define elf_addr_t Elf32_Off
#define Elf_Half Elf32_Half
@@ -403,6 +426,7 @@
extern Elf64_Dyn _DYNAMIC [];
#define elfhdr elf64_hdr
#define elf_phdr elf64_phdr
+#define elf_shdr elf64_shdr
#define elf_note elf64_note
#define elf_addr_t Elf64_Off
#define Elf_Half Elf64_Half
diff --git a/include/linux/elfcore.h b/include/linux/elfcore.h
index cfda74f..e687bc3 100644
--- a/include/linux/elfcore.h
+++ b/include/linux/elfcore.h
@@ -166,5 +166,6 @@
unsigned long limit);
extern int
elf_core_write_extra_data(struct file *file, size_t *size, unsigned long limit);
+extern size_t elf_core_extra_data_size(void);
#endif /* _LINUX_ELFCORE_H */
diff --git a/kernel/elfcore.c b/kernel/elfcore.c
index 5445741..ff915ef 100644
--- a/kernel/elfcore.c
+++ b/kernel/elfcore.c
@@ -21,3 +21,8 @@
{
return 1;
}
+
+size_t __weak elf_core_extra_data_size(void)
+{
+ return 0;
+}