Messages in this thread Patch in this message | | | From | Mathieu Desnoyers <> | Subject | [RFC PATCH for 4.18 1/2] rseq: use __u64 for rseq_cs fields, validate abort_ip < TASK_SIZE | Date | Mon, 2 Jul 2018 16:40:57 -0400 |
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Change the rseq ABI so rseq_cs start_ip, post_commit_offset and abort_ip fields are seen as 64-bit fields by both 32-bit and 64-bit kernels rather that ignoring the 32 upper bits on 32-bit kernels. This ensures we have a consistent behavior for a 32-bit binary executed on 32-bit kernels and in compat mode on 64-bit kernels.
Validating the value of abort_ip field to be below TASK_SIZE ensures the kernel don't return to an invalid address when returning to userspace after an abort. I don't fully trust each architecture code to consistently deal with invalid return addresses.
If validation fails, the process is killed with a segmentation fault.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> CC: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> CC: Peter Zijlstra <peterz@infradead.org> CC: Paul Turner <pjt@google.com> CC: Thomas Gleixner <tglx@linutronix.de> CC: Andy Lutomirski <luto@amacapital.net> CC: Andi Kleen <andi@firstfloor.org> CC: Dave Watson <davejwatson@fb.com> CC: Chris Lameter <cl@linux.com> CC: Ingo Molnar <mingo@redhat.com> CC: "H. Peter Anvin" <hpa@zytor.com> CC: Ben Maurer <bmaurer@fb.com> CC: Steven Rostedt <rostedt@goodmis.org> CC: Josh Triplett <josh@joshtriplett.org> CC: Linus Torvalds <torvalds@linux-foundation.org> CC: Andrew Morton <akpm@linux-foundation.org> CC: Russell King <linux@arm.linux.org.uk> CC: Catalin Marinas <catalin.marinas@arm.com> CC: Will Deacon <will.deacon@arm.com> CC: Michael Kerrisk <mtk.manpages@gmail.com> CC: Boqun Feng <boqun.feng@gmail.com> CC: linux-api@vger.kernel.org --- include/uapi/linux/rseq.h | 6 +++--- kernel/rseq.c | 5 +++-- 2 files changed, 6 insertions(+), 5 deletions(-)
diff --git a/include/uapi/linux/rseq.h b/include/uapi/linux/rseq.h index d620fa43756c..519ad6e176d1 100644 --- a/include/uapi/linux/rseq.h +++ b/include/uapi/linux/rseq.h @@ -52,10 +52,10 @@ struct rseq_cs { __u32 version; /* enum rseq_cs_flags */ __u32 flags; - LINUX_FIELD_u32_u64(start_ip); + __u64 start_ip; /* Offset from start_ip. */ - LINUX_FIELD_u32_u64(post_commit_offset); - LINUX_FIELD_u32_u64(abort_ip); + __u64 post_commit_offset; + __u64 abort_ip; } __attribute__((aligned(4 * sizeof(__u64)))); /* diff --git a/kernel/rseq.c b/kernel/rseq.c index 22b6acf1ad63..2e5d88f09baf 100644 --- a/kernel/rseq.c +++ b/kernel/rseq.c @@ -128,7 +128,8 @@ static int rseq_get_rseq_cs(struct task_struct *t, struct rseq_cs *rseq_cs) return 0; } urseq_cs = (struct rseq_cs __user *)ptr; - if (copy_from_user(rseq_cs, urseq_cs, sizeof(*rseq_cs))) + if (copy_from_user(rseq_cs, urseq_cs, sizeof(*rseq_cs)) || + rseq_cs->abort_ip >= TASK_SIZE) return -EFAULT; if (rseq_cs->version > 0) return -EINVAL; @@ -137,7 +138,7 @@ static int rseq_get_rseq_cs(struct task_struct *t, struct rseq_cs *rseq_cs) if (rseq_cs->abort_ip - rseq_cs->start_ip < rseq_cs->post_commit_offset) return -EINVAL; - usig = (u32 __user *)(rseq_cs->abort_ip - sizeof(u32)); + usig = (u32 __user *)(unsigned long)(rseq_cs->abort_ip - sizeof(u32)); ret = get_user(sig, usig); if (ret) return ret; -- 2.11.0
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