diff options
| author | Kees Cook <keescook@chromium.org> | 2017-07-07 21:57:29 +0300 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2018-10-03 06:10:08 +0300 |
| commit | 3c270e64a394ea5e52be9e371f5676fa974f6deb (patch) | |
| tree | 4e896af6cd19507376f9ca9be6d9280f9f398d04 | |
| parent | aba97ce870f92835fa3385861f850e3e992dc42a (diff) | |
| download | linux-3c270e64a394ea5e52be9e371f5676fa974f6deb.tar.xz | |
exec: Limit arg stack to at most 75% of _STK_LIM
commit da029c11e6b12f321f36dac8771e833b65cec962 upstream.
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>
[bwh: Backported to 3.16: replaced code is slightly different]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
| -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 70c31796a314..2acff9b648c0 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -206,8 +206,7 @@ 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 @@ -236,14 +235,16 @@ 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 > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) + limit = _STK_LIM / 4 * 3; + limit = min(limit, rlimit(RLIMIT_STACK) / 4); + if (size > limit) goto fail; } |