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authorMathieu Desnoyers <mathieu.desnoyers@efficios.com>2022-06-22 22:46:17 +0300
committerIngo Molnar <mingo@kernel.org>2022-08-01 16:21:42 +0300
commitc17a6ff9321355487d7d5ccaa7d406a0ea06b6c4 (patch)
tree42766eda34c549222a5979e8ec1c3d58e6db06c1 /kernel
parent0190e4198e47fe99d002d72588f34fd62c9ab570 (diff)
downloadlinux-c17a6ff9321355487d7d5ccaa7d406a0ea06b6c4.tar.xz
rseq: Kill process when unknown flags are encountered in ABI structures
rseq_abi()->flags and rseq_abi()->rseq_cs->flags 29 upper bits are currently unused. The current behavior when those bits are set is to ignore them. This is not an ideal behavior, because when future features will start using those flags, if user-space fails to correctly validate that the kernel indeed supports those flags (e.g. with a new sys_rseq flags bit) before using them, it may incorrectly assume that the kernel will handle those flags way when in fact those will be silently ignored on older kernels. Validating that unused flags bits are cleared will allow a smoother transition when those flags will start to be used by allowing applications to fail early, and obviously, when they attempt to use the new flags on an older kernel that does not support them. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lkml.kernel.org/r/20220622194617.1155957-2-mathieu.desnoyers@efficios.com
Diffstat (limited to 'kernel')
-rw-r--r--kernel/rseq.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/rseq.c b/kernel/rseq.c
index 81d7dc80787b..bda8175f8f99 100644
--- a/kernel/rseq.c
+++ b/kernel/rseq.c
@@ -176,7 +176,7 @@ static int rseq_need_restart(struct task_struct *t, u32 cs_flags)
u32 flags, event_mask;
int ret;
- if (WARN_ON_ONCE(cs_flags & RSEQ_CS_NO_RESTART_FLAGS))
+ if (WARN_ON_ONCE(cs_flags & RSEQ_CS_NO_RESTART_FLAGS) || cs_flags)
return -EINVAL;
/* Get thread flags. */
@@ -184,7 +184,7 @@ static int rseq_need_restart(struct task_struct *t, u32 cs_flags)
if (ret)
return ret;
- if (WARN_ON_ONCE(flags & RSEQ_CS_NO_RESTART_FLAGS))
+ if (WARN_ON_ONCE(flags & RSEQ_CS_NO_RESTART_FLAGS) || flags)
return -EINVAL;
/*