diff options
author | Gustavo A. R. Silva <gustavo@embeddedor.com> | 2018-05-25 14:47:57 -0700 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-05-30 07:51:50 +0200 |
commit | 058dfcf9c24f74f30a78f7c837b784054736cdf1 (patch) | |
tree | 382faf07aedf28ec9e9f5ba4f4a393f6a1e3cfd4 | |
parent | 1da530fe155d8c0d93d532ebd0df03955ebf931d (diff) |
kernel/sys.c: fix potential Spectre v1 issue
commit 23d6aef74da86a33fa6bb75f79565e0a16ee97c2 upstream.
`resource' can be controlled by user-space, hence leading to a potential
exploitation of the Spectre variant 1 vulnerability.
This issue was detected with the help of Smatch:
kernel/sys.c:1474 __do_compat_sys_old_getrlimit() warn: potential spectre issue 'get_current()->signal->rlim' (local cap)
kernel/sys.c:1455 __do_sys_old_getrlimit() warn: potential spectre issue 'get_current()->signal->rlim' (local cap)
Fix this by sanitizing *resource* before using it to index
current->signal->rlim
Notice that given that speculation windows are large, the policy is to
kill the speculation on the first load and not worry if it can be
completed with a dependent load/store [1].
[1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2
Link: http://lkml.kernel.org/r/20180515030038.GA11822@embeddedor.com
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r-- | kernel/sys.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/sys.c b/kernel/sys.c index b5c1bc9e3769..de4ed027dfd7 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -1395,6 +1395,7 @@ SYSCALL_DEFINE2(old_getrlimit, unsigned int, resource, if (resource >= RLIM_NLIMITS) return -EINVAL; + resource = array_index_nospec(resource, RLIM_NLIMITS); task_lock(current->group_leader); x = current->signal->rlim[resource]; task_unlock(current->group_leader); @@ -1414,6 +1415,7 @@ COMPAT_SYSCALL_DEFINE2(old_getrlimit, unsigned int, resource, if (resource >= RLIM_NLIMITS) return -EINVAL; + resource = array_index_nospec(resource, RLIM_NLIMITS); task_lock(current->group_leader); r = current->signal->rlim[resource]; task_unlock(current->group_leader); |