coredump: pass mm->flags as a coredump parameter for consistency
Pass mm->flags as a coredump parameter for consistency.
---
1787 if (mm->core_state || !get_dumpable(mm)) { <- (1)
1788 up_write(&mm->mmap_sem);
1789 put_cred(cred);
1790 goto fail;
1791 }
1792
[...]
1798 if (get_dumpable(mm) == 2) { /* Setuid core dump mode */ <-(2)
1799 flag = O_EXCL; /* Stop rewrite attacks */
1800 cred->fsuid = 0; /* Dump root private */
1801 }
---
Since dumpable bits are not protected by lock, there is a chance to change
these bits between (1) and (2).
To solve this issue, this patch copies mm->flags to
coredump_params.mm_flags at the beginning of do_coredump() and uses it
instead of get_dumpable() while dumping core.
This copy is also passed to binfmt->core_dump, since elf*_core_dump() uses
dump_filter bits in mm->flags.
[akpm@linux-foundation.org: fix merge]
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Acked-by: Roland McGrath <roland@redhat.com>
Cc: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.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 78de530..535e763 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1882,7 +1882,6 @@
struct vm_area_struct *vma, *gate_vma;
struct elfhdr *elf = NULL;
loff_t offset = 0, dataoff, foffset;
- unsigned long mm_flags;
struct elf_note_info info;
struct elf_phdr *phdr4note = NULL;
struct elf_shdr *shdr4extnum = NULL;
@@ -1957,14 +1956,7 @@
dataoff = offset = roundup(offset, ELF_EXEC_PAGESIZE);
- /*
- * We must use the same mm->flags while dumping core to avoid
- * inconsistency between the program headers and bodies, otherwise an
- * unusable core file can be generated.
- */
- mm_flags = current->mm->flags;
-
- offset += elf_core_vma_data_size(gate_vma, mm_flags);
+ offset += elf_core_vma_data_size(gate_vma, cprm->mm_flags);
offset += elf_core_extra_data_size();
e_shoff = offset;
@@ -1995,7 +1987,7 @@
phdr.p_offset = offset;
phdr.p_vaddr = vma->vm_start;
phdr.p_paddr = 0;
- phdr.p_filesz = vma_dump_size(vma, mm_flags);
+ phdr.p_filesz = vma_dump_size(vma, cprm->mm_flags);
phdr.p_memsz = vma->vm_end - vma->vm_start;
offset += phdr.p_filesz;
phdr.p_flags = vma->vm_flags & VM_READ ? PF_R : 0;
@@ -2030,7 +2022,7 @@
unsigned long addr;
unsigned long end;
- end = vma->vm_start + vma_dump_size(vma, mm_flags);
+ end = vma->vm_start + vma_dump_size(vma, cprm->mm_flags);
for (addr = vma->vm_start; addr < end; addr += PAGE_SIZE) {
struct page *page;