fs/binfmt_elf.c: fix internal inconsistency relating to vma dump size
vma_dump_size() has been used several times on actual dumper and it is
supposed to return the same value for the same vma. But vma_dump_size()
could return different values for same vma.
The known problem case is concurrent shared memory removal. If a vma is
used for a shared memory and that shared memory is removed between
writing program header and dumping vma memory, this will result in a
dump file which is internally consistent.
To fix the problem, we set baseline to get dump size and store the size
into vma_filesz and always use the same vma dump size which is stored in
vma_filsz. The consistnecy with reality is not actually guranteed, but
it's tolerable since that is fully consistent with base line.
Signed-off-by: Jungseung Lee <js07.lee@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index d8fc060..3a6175f 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1994,18 +1994,6 @@
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
*
@@ -2017,7 +2005,8 @@
{
int has_dumped = 0;
mm_segment_t fs;
- int segs;
+ int segs, i;
+ size_t vma_data_size = 0;
struct vm_area_struct *vma, *gate_vma;
struct elfhdr *elf = NULL;
loff_t offset = 0, dataoff;
@@ -2026,6 +2015,7 @@
struct elf_shdr *shdr4extnum = NULL;
Elf_Half e_phnum;
elf_addr_t e_shoff;
+ elf_addr_t *vma_filesz = NULL;
/*
* We no longer stop all VM operations.
@@ -2093,7 +2083,20 @@
dataoff = offset = roundup(offset, ELF_EXEC_PAGESIZE);
- offset += elf_core_vma_data_size(gate_vma, cprm->mm_flags);
+ vma_filesz = kmalloc_array(segs - 1, sizeof(*vma_filesz), GFP_KERNEL);
+ if (!vma_filesz)
+ goto end_coredump;
+
+ for (i = 0, vma = first_vma(current, gate_vma); vma != NULL;
+ vma = next_vma(vma, gate_vma)) {
+ unsigned long dump_size;
+
+ dump_size = vma_dump_size(vma, cprm->mm_flags);
+ vma_filesz[i++] = dump_size;
+ vma_data_size += dump_size;
+ }
+
+ offset += vma_data_size;
offset += elf_core_extra_data_size();
e_shoff = offset;
@@ -2113,7 +2116,7 @@
goto end_coredump;
/* Write program headers for segments dump */
- for (vma = first_vma(current, gate_vma); vma != NULL;
+ for (i = 0, vma = first_vma(current, gate_vma); vma != NULL;
vma = next_vma(vma, gate_vma)) {
struct elf_phdr phdr;
@@ -2121,7 +2124,7 @@
phdr.p_offset = offset;
phdr.p_vaddr = vma->vm_start;
phdr.p_paddr = 0;
- phdr.p_filesz = vma_dump_size(vma, cprm->mm_flags);
+ phdr.p_filesz = vma_filesz[i++];
phdr.p_memsz = vma->vm_end - vma->vm_start;
offset += phdr.p_filesz;
phdr.p_flags = vma->vm_flags & VM_READ ? PF_R : 0;
@@ -2149,12 +2152,12 @@
if (!dump_skip(cprm, dataoff - cprm->written))
goto end_coredump;
- for (vma = first_vma(current, gate_vma); vma != NULL;
+ for (i = 0, vma = first_vma(current, gate_vma); vma != NULL;
vma = next_vma(vma, gate_vma)) {
unsigned long addr;
unsigned long end;
- end = vma->vm_start + vma_dump_size(vma, cprm->mm_flags);
+ end = vma->vm_start + vma_filesz[i++];
for (addr = vma->vm_start; addr < end; addr += PAGE_SIZE) {
struct page *page;
@@ -2187,6 +2190,7 @@
cleanup:
free_note_info(&info);
kfree(shdr4extnum);
+ kfree(vma_filesz);
kfree(phdr4note);
kfree(elf);
out: