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

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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 <[email protected]>
Cc: KOSAKI Motohiro <[email protected]>
Cc: [email protected]
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Oleg Nesterov 2010-11-30 20:56:02 +01:00 • committed by Linus Torvalds
commit 114279be21
3 changed files with 23 additions and 17 deletions
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28
fs/compat.c
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@ -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) {