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_fdpic.c b/fs/binfmt_elf_fdpic.c
index e49d9c0..6d6a16c 100644
--- a/fs/binfmt_elf_fdpic.c
+++ b/fs/binfmt_elf_fdpic.c
@@ -1626,7 +1626,6 @@
#endif
int thread_status_size = 0;
elf_addr_t *auxv;
- unsigned long mm_flags;
struct elf_phdr *phdr4note = NULL;
struct elf_shdr *shdr4extnum = NULL;
Elf_Half e_phnum;
@@ -1769,14 +1768,7 @@
/* Page-align dumped data */
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(mm_flags);
+ offset += elf_core_vma_data_size(cprm->mm_flags);
offset += elf_core_extra_data_size();
e_shoff = offset;
@@ -1809,7 +1801,7 @@
phdr.p_offset = offset;
phdr.p_vaddr = vma->vm_start;
phdr.p_paddr = 0;
- phdr.p_filesz = maydump(vma, mm_flags) ? sz : 0;
+ phdr.p_filesz = maydump(vma, cprm->mm_flags) ? sz : 0;
phdr.p_memsz = sz;
offset += phdr.p_filesz;
phdr.p_flags = vma->vm_flags & VM_READ ? PF_R : 0;
@@ -1847,7 +1839,7 @@
goto end_coredump;
if (elf_fdpic_dump_segments(cprm->file, &size, &cprm->limit,
- mm_flags) < 0)
+ cprm->mm_flags) < 0)
goto end_coredump;
if (!elf_core_write_extra_data(cprm->file, &size, cprm->limit))