[PATCH 160/173] exec: copy-and-paste the fixes into compat_do_execve() paths

From: Willy Tarreau
Date: Mon Apr 25 2011 - 16:30:51 EST


2.6.27.59-stable review patch. If anyone has any objections, please let us know.

------------------

From: Oleg Nesterov <oleg@xxxxxxxxxx>

commit 114279be2120a916e8a04feeb2ac976a10016f2f upstream.

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@xxxxxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: Moritz Muehlenhoff <jmm@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
fs/compat.c | 28 +++++++++++++++-------------
fs/exec.c | 8 ++++----
include/linux/binfmts.h | 4 ++++
3 files changed, 23 insertions(+), 17 deletions(-)

Index: longterm-2.6.27/fs/compat.c
===================================================================
--- longterm-2.6.27.orig/fs/compat.c 2011-01-23 10:52:28.000000000 +0100
+++ longterm-2.6.27/fs/compat.c 2011-04-25 17:24:25.210282944 +0200
@@ -1241,6 +1241,10 @@
argv++;
if(++i > max)
return -E2BIG;
+
+ if (fatal_signal_pending(current))
+ return -ERESTARTNOHAND;
+ cond_resched();
}
}
return i;
@@ -1282,6 +1286,12 @@
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;
@@ -1298,18 +1308,8 @@
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;
}
@@ -1425,8 +1425,10 @@
security_bprm_free(bprm);

out_mm:
- if (bprm->mm)
+ if (bprm->mm) {
+ acct_arg_size(bprm, 0);
mmput(bprm->mm);
+ }

out_file:
if (bprm->file) {
Index: longterm-2.6.27/fs/exec.c
===================================================================
--- longterm-2.6.27.orig/fs/exec.c 2011-04-25 17:22:50.000000000 +0200
+++ longterm-2.6.27/fs/exec.c 2011-04-25 17:23:56.746278475 +0200
@@ -168,7 +168,7 @@

#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 @@
up_write(&mm->mmap_sem);
}

-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;
@@ -308,11 +308,11 @@

#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;
Index: longterm-2.6.27/include/linux/binfmts.h
===================================================================
--- longterm-2.6.27.orig/include/linux/binfmts.h 2011-04-25 17:22:24.000000000 +0200
+++ longterm-2.6.27/include/linux/binfmts.h 2011-04-25 17:23:56.751278452 +0200
@@ -53,6 +53,10 @@
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)



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