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    Subject[PATCH] [135/223] exec: copy-and-paste the fixes into compat_do_execve() paths
    Date
    2.6.35-longterm review patch.  If anyone has any objections, please let me know.

    ------------------
    From: Oleg Nesterov <oleg@redhat.com>

    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@redhat.com>
    Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
    Signed-off-by: Andi Kleen <ak@linux.intel.com>

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

    Index: linux/fs/compat.c
    ===================================================================
    --- linux.orig/fs/compat.c
    +++ linux/fs/compat.c
    @@ -1376,6 +1376,10 @@ static int compat_count(compat_uptr_t __
    argv++;
    if (i++ >= max)
    return -E2BIG;
    +
    + if (fatal_signal_pending(current))
    + return -ERESTARTNOHAND;
    + cond_resched();
    }
    }
    return i;
    @@ -1417,6 +1421,12 @@ static int compat_copy_strings(int argc,
    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;
    @@ -1433,18 +1443,8 @@ static int compat_copy_strings(int argc,
    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;
    }
    @@ -1565,8 +1565,10 @@ 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) {
    Index: linux/fs/exec.c
    ===================================================================
    --- linux.orig/fs/exec.c
    +++ linux/fs/exec.c
    @@ -158,7 +158,7 @@ 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);
    @@ -177,7 +177,7 @@ static void acct_arg_size(struct linux_b
    #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;
    @@ -291,11 +291,11 @@ static bool valid_arg_len(struct linux_b

    #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: linux/include/linux/binfmts.h
    ===================================================================
    --- linux.orig/include/linux/binfmts.h
    +++ linux/include/linux/binfmts.h
    @@ -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)


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