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| author | Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | 2013-09-11 14:23:18 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-09-11 15:58:18 -0700 |
| commit | 3ddc5b46a8e90f3c9251338b60191d0a804b0d92 (patch) | |
| tree | 5c76cd730cb94e75f30953d6cd1aed9386fcee37 /arch/alpha | |
| parent | 20d0e57017b69e7e4ae7166c43f3a3f023ab9702 (diff) | |
| download | lwn-3ddc5b46a8e90f3c9251338b60191d0a804b0d92.tar.gz lwn-3ddc5b46a8e90f3c9251338b60191d0a804b0d92.zip | |
kernel-wide: fix missing validations on __get/__put/__copy_to/__copy_from_user()
I found the following pattern that leads in to interesting findings:
grep -r "ret.*|=.*__put_user" *
grep -r "ret.*|=.*__get_user" *
grep -r "ret.*|=.*__copy" *
The __put_user() calls in compat_ioctl.c, ptrace compat, signal compat,
since those appear in compat code, we could probably expect the kernel
addresses not to be reachable in the lower 32-bit range, so I think they
might not be exploitable.
For the "__get_user" cases, I don't think those are exploitable: the worse
that can happen is that the kernel will copy kernel memory into in-kernel
buffers, and will fail immediately afterward.
The alpha csum_partial_copy_from_user() seems to be missing the
access_ok() check entirely. The fix is inspired from x86. This could
lead to information leak on alpha. I also noticed that many architectures
map csum_partial_copy_from_user() to csum_partial_copy_generic(), but I
wonder if the latter is performing the access checks on every
architectures.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/alpha')
| -rw-r--r-- | arch/alpha/lib/csum_partial_copy.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/alpha/lib/csum_partial_copy.c b/arch/alpha/lib/csum_partial_copy.c index 40736da9bea8..ffb19b7da999 100644 --- a/arch/alpha/lib/csum_partial_copy.c +++ b/arch/alpha/lib/csum_partial_copy.c @@ -338,6 +338,11 @@ csum_partial_copy_from_user(const void __user *src, void *dst, int len, unsigned long doff = 7 & (unsigned long) dst; if (len) { + if (!access_ok(VERIFY_READ, src, len)) { + *errp = -EFAULT; + memset(dst, 0, len); + return sum; + } if (!doff) { if (!soff) checksum = csum_partial_cfu_aligned( |