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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org,
	Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
	Steven Rostedt <rostedt@goodmis.org>
Subject: [PATCH 3.14 54/98] ftrace/jprobes/x86: Fix conflict between jprobes and function graph tracing
Date: Sun, 25 Jan 2015 10:07:12 -0800	[thread overview]
Message-ID: <20150125180715.200699878@linuxfoundation.org> (raw)
In-Reply-To: <20150125180712.859646324@linuxfoundation.org>

3.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

commit 237d28db036e411f22c03cfd5b0f6dc2aa9bf3bc upstream.

If the function graph tracer traces a jprobe callback, the system will
crash. This can easily be demonstrated by compiling the jprobe
sample module that is in the kernel tree, loading it and running the
function graph tracer.

 # modprobe jprobe_example.ko
 # echo function_graph > /sys/kernel/debug/tracing/current_tracer
 # ls

The first two commands end up in a nice crash after the first fork.
(do_fork has a jprobe attached to it, so "ls" just triggers that fork)

The problem is caused by the jprobe_return() that all jprobe callbacks
must end with. The way jprobes works is that the function a jprobe
is attached to has a breakpoint placed at the start of it (or it uses
ftrace if fentry is supported). The breakpoint handler (or ftrace callback)
will copy the stack frame and change the ip address to return to the
jprobe handler instead of the function. The jprobe handler must end
with jprobe_return() which swaps the stack and does an int3 (breakpoint).
This breakpoint handler will then put back the saved stack frame,
simulate the instruction at the beginning of the function it added
a breakpoint to, and then continue on.

For function tracing to work, it hijakes the return address from the
stack frame, and replaces it with a hook function that will trace
the end of the call. This hook function will restore the return
address of the function call.

If the function tracer traces the jprobe handler, the hook function
for that handler will not be called, and its saved return address
will be used for the next function. This will result in a kernel crash.

To solve this, pause function tracing before the jprobe handler is called
and unpause it before it returns back to the function it probed.

Some other updates:

Used a variable "saved_sp" to hold kcb->jprobe_saved_sp. This makes the
code look a bit cleaner and easier to understand (various tries to fix
this bug required this change).

Note, if fentry is being used, jprobes will change the ip address before
the function graph tracer runs and it will not be able to trace the
function that the jprobe is probing.

Link: http://lkml.kernel.org/r/20150114154329.552437962@goodmis.org

Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/x86/kernel/kprobes/core.c |   20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -1017,6 +1017,15 @@ int __kprobes setjmp_pre_handler(struct
 	regs->flags &= ~X86_EFLAGS_IF;
 	trace_hardirqs_off();
 	regs->ip = (unsigned long)(jp->entry);
+
+	/*
+	 * jprobes use jprobe_return() which skips the normal return
+	 * path of the function, and this messes up the accounting of the
+	 * function graph tracer to get messed up.
+	 *
+	 * Pause function graph tracing while performing the jprobe function.
+	 */
+	pause_graph_tracing();
 	return 1;
 }
 
@@ -1042,24 +1051,25 @@ int __kprobes longjmp_break_handler(stru
 	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
 	u8 *addr = (u8 *) (regs->ip - 1);
 	struct jprobe *jp = container_of(p, struct jprobe, kp);
+	void *saved_sp = kcb->jprobe_saved_sp;
 
 	if ((addr > (u8 *) jprobe_return) &&
 	    (addr < (u8 *) jprobe_return_end)) {
-		if (stack_addr(regs) != kcb->jprobe_saved_sp) {
+		if (stack_addr(regs) != saved_sp) {
 			struct pt_regs *saved_regs = &kcb->jprobe_saved_regs;
 			printk(KERN_ERR
 			       "current sp %p does not match saved sp %p\n",
-			       stack_addr(regs), kcb->jprobe_saved_sp);
+			       stack_addr(regs), saved_sp);
 			printk(KERN_ERR "Saved registers for jprobe %p\n", jp);
 			show_regs(saved_regs);
 			printk(KERN_ERR "Current registers\n");
 			show_regs(regs);
 			BUG();
 		}
+		/* It's OK to start function graph tracing again */
+		unpause_graph_tracing();
 		*regs = kcb->jprobe_saved_regs;
-		memcpy((kprobe_opcode_t *)(kcb->jprobe_saved_sp),
-		       kcb->jprobes_stack,
-		       MIN_STACK_SIZE(kcb->jprobe_saved_sp));
+		memcpy(saved_sp, kcb->jprobes_stack, MIN_STACK_SIZE(saved_sp));
 		preempt_enable_no_resched();
 		return 1;
 	}



  parent reply	other threads:[~2015-01-25 19:17 UTC|newest]

Thread overview: 96+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-25 18:06 [PATCH 3.14 00/98] 3.14.30-stable review Greg Kroah-Hartman
2015-01-25 18:06 ` [PATCH 3.14 02/98] netlink: Always copy on mmap TX Greg Kroah-Hartman
2015-01-25 18:06 ` [PATCH 3.14 03/98] netlink: Dont reorder loads/stores before marking mmap netlink frame as available Greg Kroah-Hartman
2015-01-25 18:06 ` [PATCH 3.14 04/98] in6: fix conflict with glibc Greg Kroah-Hartman
2015-01-25 18:06 ` [PATCH 3.14 05/98] tg3: tg3_disable_ints using uninitialized mailbox value to disable interrupts Greg Kroah-Hartman
2015-01-25 18:06 ` [PATCH 3.14 07/98] batman-adv: Unify fragment size calculation Greg Kroah-Hartman
2015-01-25 18:06 ` [PATCH 3.14 08/98] batman-adv: avoid NULL dereferences and fix if check Greg Kroah-Hartman
2015-01-25 18:06 ` [PATCH 3.14 09/98] net: Fix stacked vlan offload features computation Greg Kroah-Hartman
2015-01-25 18:06 ` [PATCH 3.14 10/98] net: Reset secmark when scrubbing packet Greg Kroah-Hartman
2015-01-25 18:06 ` [PATCH 3.14 11/98] tcp: Do not apply TSO segment limit to non-TSO packets Greg Kroah-Hartman
2015-01-25 18:06 ` [PATCH 3.14 12/98] alx: fix alx_poll() Greg Kroah-Hartman
2015-01-25 18:06 ` [PATCH 3.14 13/98] team: avoid possible underflow of count_pending value for notify_peers and mcast_rejoin Greg Kroah-Hartman
2015-01-25 18:06 ` [PATCH 3.14 14/98] enic: fix rx skb checksum Greg Kroah-Hartman
2015-01-25 18:06 ` [PATCH 3.14 15/98] net/core: Handle csum for CHECKSUM_COMPLETE VXLAN forwarding Greg Kroah-Hartman
2015-01-25 18:06 ` [PATCH 3.14 16/98] drm/vmwgfx: Fix fence event code Greg Kroah-Hartman
2015-01-25 18:06 ` [PATCH 3.14 17/98] drm/ttm: Avoid memory allocation from shrinker functions Greg Kroah-Hartman
2015-01-25 18:06 ` [PATCH 3.14 18/98] drm/radeon: fix typo in CI dpm disable Greg Kroah-Hartman
2015-01-25 18:06 ` [PATCH 3.14 19/98] drm/radeon: work around a hw bug in MGCG on CIK Greg Kroah-Hartman
2015-01-25 18:06 ` [PATCH 3.14 21/98] drm/radeon: properly filter DP1.2 4k modes on non-DP1.2 hw Greg Kroah-Hartman
2015-01-25 18:06 ` [PATCH 3.14 22/98] drm/i915: Dont complain about stolen conflicts on gen3 Greg Kroah-Hartman
2015-01-25 18:06 ` [PATCH 3.14 23/98] drm/i915: Only warn the first time we attempt to mmio whilst suspended Greg Kroah-Hartman
2015-01-25 18:06 ` [PATCH 3.14 24/98] drm/nv4c/mc: disable msi Greg Kroah-Hartman
2015-01-25 18:06 ` [PATCH 3.14 27/98] ARC: [nsimosci] move peripherals to match model to FPGA Greg Kroah-Hartman
2015-01-25 18:06 ` [PATCH 3.14 28/98] ARC: switch to generic ENTRY/END assembler annotations Greg Kroah-Hartman
2015-01-25 18:06 ` [PATCH 3.14 29/98] cfg80211: dont WARN about two consecutive Country IE hint Greg Kroah-Hartman
2015-01-25 18:06 ` [PATCH 3.14 30/98] cfg80211: avoid mem leak on driver hint set Greg Kroah-Hartman
2015-01-25 18:06 ` [PATCH 3.14 31/98] cfg80211: Fix 160 MHz channels with 80+80 and 160 MHz drivers Greg Kroah-Hartman
2015-01-25 18:06 ` [PATCH 3.14 32/98] hp_accel: Add support for HP ZBook 15 Greg Kroah-Hartman
2015-01-25 18:06 ` [PATCH 3.14 33/98] tick/powerclamp: Remove tick_nohz_idle abuse Greg Kroah-Hartman
2015-01-25 18:06 ` [PATCH 3.14 34/98] genirq: Prevent proc race against freeing of irq descriptors Greg Kroah-Hartman
2015-01-25 18:06 ` [PATCH 3.14 35/98] iscsi-target: Fail connection on short sendmsg writes Greg Kroah-Hartman
2015-01-25 18:06 ` [PATCH 3.14 36/98] Revert "[SCSI] mpt2sas: Remove phys on topology change." Greg Kroah-Hartman
2015-01-25 18:06 ` [PATCH 3.14 37/98] Revert "[SCSI] mpt3sas: Remove phys on topology change" Greg Kroah-Hartman
2015-01-25 18:06 ` [PATCH 3.14 38/98] scsi: blacklist RSOC for Microsoft iSCSI target devices Greg Kroah-Hartman
2015-01-25 18:06 ` [PATCH 3.14 39/98] clk: samsung: Fix double add of syscore ops after driver rebind Greg Kroah-Hartman
2015-01-25 18:06 ` [PATCH 3.14 40/98] clk: Really fix deadlock with mmap_sem Greg Kroah-Hartman
2015-01-26 12:46   ` Luis Henriques
2015-01-26 22:20     ` Greg Kroah-Hartman
2015-01-25 18:06 ` [PATCH 3.14 41/98] clk: Dont try to use a struct clk* after it could have been freed Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 42/98] parisc: fix out-of-register compiler error in ldcw inline assembler function Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 43/98] storvsc: ring buffer failures may result in I/O freeze Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 44/98] net: ethernet: cpsw: fix hangs with interrupts Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 45/98] video/logo: prevent use of logos after they have been freed Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 46/98] [media] smiapp-pll: Correct clock debug prints Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 48/98] [media] smiapp: Take mutex during PLL update in sensor initialisation Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 49/98] [media] sound: simplify au0828 quirk table Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 50/98] [media] sound: Update au0828 quirks table Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 51/98] [media] uvcvideo: Fix destruction order in uvc_delete() Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 52/98] vfio-pci: Fix the check on pci device type in vfio_pci_probe() Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 53/98] drivers: net: cpsw: fix multicast flush in dual emac mode Greg Kroah-Hartman
2015-01-25 18:07 ` Greg Kroah-Hartman [this message]
2015-01-25 18:07 ` [PATCH 3.14 55/98] NFSv4.1: Fix client id trunking on Linux Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 56/98] gpiolib: of: Correct error handling in of_get_named_gpiod_flags Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 57/98] gpio: fix memory and reference leaks in gpiochip_add error path Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 58/98] OHCI: add a quirk for ULi M5237 blocking on reset Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 59/98] usb: dwc3: gadget: Fix TRB preparation during SG Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 60/98] usb: dwc3: gadget: Stop TRB preparation after limit is reached Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 61/98] USB: cp210x: fix ID for production CEL MeshConnect USB Stick Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 62/98] USB: cp210x: add IDs for CEL USB sticks and MeshWorks devices Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 63/98] USB: keyspan: fix null-deref at probe Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 64/98] USB: console: fix uninitialised ldisc semaphore Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 65/98] USB: console: fix potential use after free Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 66/98] USB: EHCI: fix initialization bug in iso_stream_schedule() Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 67/98] usb: musb: stuff leak of struct usb_hcd Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 68/98] can: kvaser_usb: Dont free packets when tight on URBs Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 69/98] can: kvaser_usb: Reset all URB tx contexts upon channel close Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 70/98] can: kvaser_usb: Dont send a RESET_CHIP for non-existing channels Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 72/98] Input: I8042 - add Acer Aspire 7738 to the nomux list Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 73/98] ARM: dts: imx25: Fix the SPI1 clocks Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 74/98] ARM: imx6q: drop unnecessary semicolon Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 75/98] ARM: clk-imx6q: fix video divider for rev T0 1.0 Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 76/98] ARM: omap5/dra7xx: Fix frequency typos Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 77/98] ARM: shmobile: sh73a0 legacy: Set .control_parent for all irqpin instances Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 78/98] decompress_bunzip2: off by one in get_next_block() Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 79/98] um: Skip futex_atomic_cmpxchg_inatomic() test Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 80/98] x86, um: actually mark system call tables readonly Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 81/98] LOCKD: Fix a race when initialising nlmsvc_timeout Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 82/98] tcm_loop: Fixup tag handling Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 83/98] tcm_loop: Fix wrong I_T nexus association Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 84/98] vhost-scsi: Add missing virtio-scsi -> TCM attribute conversion Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 85/98] iscsi,iser-target: Initiate termination only once Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 86/98] iser-target: Fix flush + disconnect completion handling Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 87/98] iser-target: Parallelize CM connection establishment Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 88/98] iser-target: Fix connected_handler + teardown flow race Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 89/98] iser-target: Handle ADDR_CHANGE event for listener cm_id Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 90/98] iser-target: Fix implicit termination of connections Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 91/98] bcache: Make sure to pass GFP_WAIT to mempool_alloc() Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 92/98] KVM: nVMX: Disable unrestricted mode if ept=0 Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 93/98] netfilter: ipset: small potential read beyond the end of buffer Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 94/98] net: prevent of emerging cross-namespace symlinks Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 95/98] net: fix creation adjacent device symlinks Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 96/98] fsnotify: next_i is freed during fsnotify_unmount_inodes Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 97/98] s390/3215: fix hanging console issue Greg Kroah-Hartman
2015-01-25 18:07 ` [PATCH 3.14 98/98] s390/3215: fix tty output containing tabs Greg Kroah-Hartman
2015-01-25 21:37 ` [PATCH 3.14 00/98] 3.14.30-stable review Guenter Roeck
2015-01-26 17:43 ` Shuah Khan

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