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exec: copy-and-paste the fixes into compat_do_execve() paths 

Note: this patch targets 2.6.37 and tries to be as simple as possible.
That is why it adds more copy-and-paste horror into fs/compat.c and
uglifies fs/exec.c, this will be cleanuped later.

compat_copy_strings() plays with bprm->vma/mm directly and thus has
two problems: it lacks the RLIMIT_STACK check and argv/envp memory
is not visible to oom killer.

Export acct_arg_size() and get_arg_page(), change compat_copy_strings()
to use get_arg_page(), change compat_do_execve() to do acct_arg_size(0)
as do_execve() does.

Add the fatal_signal_pending/cond_resched checks into compat_count() and
compat_copy_strings(), this matches the code in fs/exec.c and certainly
makes sense.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Oleg Nesterov 2010-11-30 20:56:02 +01:00 committed by Linus Torvalds
parent 3c77f84572
commit 114279be21
3 changed files with 23 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

28
fs/compat.c
View File

@ -1350,6 +1350,10 @@ static int compat_count(compat_uptr_t __user *argv, int max)
argv++;
if (i++ >= max)
return -E2BIG;
if (fatal_signal_pending(current))
return -ERESTARTNOHAND;
cond_resched();
}
}
return i;
@ -1391,6 +1395,12 @@ static int compat_copy_strings(int argc, compat_uptr_t __user *argv,
while (len > 0) {
int offset, bytes_to_copy;
if (fatal_signal_pending(current)) {
ret = -ERESTARTNOHAND;
goto out;
}
cond_resched();
offset = pos % PAGE_SIZE;
if (offset == 0)
offset = PAGE_SIZE;
@ -1407,18 +1417,8 @@ static int compat_copy_strings(int argc, compat_uptr_t __user *argv,
if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
struct page *page;
#ifdef CONFIG_STACK_GROWSUP
ret = expand_stack_downwards(bprm->vma, pos);
if (ret < 0) {
/* We've exceed the stack rlimit. */
ret = -E2BIG;
goto out;
}
#endif
ret = get_user_pages(current, bprm->mm, pos,
1, 1, 1, &page, NULL);
if (ret <= 0) {
/* We've exceed the stack rlimit. */
page = get_arg_page(bprm, pos, 1);
if (!page) {
ret = -E2BIG;
goto out;
}
@ -1539,8 +1539,10 @@ int compat_do_execve(char * filename,
return retval;
out:
if (bprm->mm)
if (bprm->mm) {
acct_arg_size(bprm, 0);
mmput(bprm->mm);
}
out_file:
if (bprm->file) {

8
fs/exec.c
View File

@ -164,7 +164,7 @@ out:
#ifdef CONFIG_MMU
static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
{
struct mm_struct *mm = current->mm;
long diff = (long)(pages - bprm->vma_pages);
@ -183,7 +183,7 @@ static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
#endif
}
static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
int write)
{
struct page *page;
@ -297,11 +297,11 @@ static bool valid_arg_len(struct linux_binprm *bprm, long len)
#else
static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
{
}
static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
int write)
{
struct page *page;

4
include/linux/binfmts.h
View File

@ -60,6 +60,10 @@ struct linux_binprm{
unsigned long loader, exec;
};
extern void acct_arg_size(struct linux_binprm *bprm, unsigned long pages);
extern struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
int write);
#define BINPRM_FLAGS_ENFORCE_NONDUMP_BIT 0
#define BINPRM_FLAGS_ENFORCE_NONDUMP (1 << BINPRM_FLAGS_ENFORCE_NONDUMP_BIT)