4.14-stable review patch. If anyone has any objections, please let me know.
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From: Mark Rutland mark.rutland@arm.com
[ Upstream commit 19791a7ca674fb3009bb068260e852a2f05b605c ]
It's possible for userspace to control idx. Sanitize idx when using it as an array index.
Found by smatch.
Signed-off-by: Mark Rutland mark.rutland@arm.com Cc: Catalin Marinas catalin.marinas@arm.com Cc: Will Deacon will.deacon@arm.com Signed-off-by: Will Deacon will.deacon@arm.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/arm64/kernel/ptrace.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-)
--- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -25,6 +25,7 @@ #include <linux/sched/signal.h> #include <linux/sched/task_stack.h> #include <linux/mm.h> +#include <linux/nospec.h> #include <linux/smp.h> #include <linux/ptrace.h> #include <linux/user.h> @@ -247,15 +248,20 @@ static struct perf_event *ptrace_hbp_get
switch (note_type) { case NT_ARM_HW_BREAK: - if (idx < ARM_MAX_BRP) - bp = tsk->thread.debug.hbp_break[idx]; + if (idx >= ARM_MAX_BRP) + goto out; + idx = array_index_nospec(idx, ARM_MAX_BRP); + bp = tsk->thread.debug.hbp_break[idx]; break; case NT_ARM_HW_WATCH: - if (idx < ARM_MAX_WRP) - bp = tsk->thread.debug.hbp_watch[idx]; + if (idx >= ARM_MAX_WRP) + goto out; + idx = array_index_nospec(idx, ARM_MAX_WRP); + bp = tsk->thread.debug.hbp_watch[idx]; break; }
+out: return bp; }