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| author | Kees Cook <keescook@chromium.org> | 2017-07-07 11:57:29 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-07-07 20:05:08 -0700 |
| commit | da029c11e6b12f321f36dac8771e833b65cec962 (patch) | |
| tree | 0ba6e0c9338f1b3de6498793ecff2643c4fd289c | |
| parent | 088737f44bbf6378745f5b57b035e57ee3dc4750 (diff) | |
| download | linux-da029c11e6b12f321f36dac8771e833b65cec962.tar.gz | |
exec: Limit arg stack to at most 75% of _STK_LIM
To avoid pathological stack usage or the need to special-case setuid execs, just limit all arg stack usage to at most 75% of _STK_LIM (6MB). Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | fs/exec.c | 11 |
1 files changed, 6 insertions, 5 deletions
diff --git a/fs/exec.c b/fs/exec.c index 904199086490..62175cbcc801 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -220,8 +220,7 @@ static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, if (write) { unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start; - unsigned long ptr_size; - struct rlimit *rlim; + unsigned long ptr_size, limit; /* * Since the stack will hold pointers to the strings, we @@ -250,14 +249,16 @@ static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, return page; /* - * Limit to 1/4-th the stack size for the argv+env strings. + * Limit to 1/4 of the max stack size or 3/4 of _STK_LIM + * (whichever is smaller) for the argv+env strings. * This ensures that: * - the remaining binfmt code will not run out of stack space, * - the program will have a reasonable amount of stack left * to work from. */ - rlim = current->signal->rlim; - if (size > READ_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) + limit = _STK_LIM / 4 * 3; + limit = min(limit, rlimit(RLIMIT_STACK) / 4); + if (size > limit) goto fail; } |