From mboxrd@z Thu Jan 1 00:00:00 1970 From: rabin@rab.in (Rabin Vincent) Date: Sun, 20 Dec 2015 16:29:39 +0100 Subject: [PATCH V7 02/24] coresight: associating path with session rather than tracer In-Reply-To: <1450472361-426-3-git-send-email-mathieu.poirier@linaro.org> References: <1450472361-426-1-git-send-email-mathieu.poirier@linaro.org> <1450472361-426-3-git-send-email-mathieu.poirier@linaro.org> Message-ID: <20151220152939.GA11552@debian> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Fri, Dec 18, 2015 at 01:58:58PM -0700, Mathieu Poirier wrote: > When using the Coresight framework from the sysFS interface a > tracer is always handling a single session and as such, a path > can be associated with a tracer. But when supporting multiple > session per tracer there is no guarantee that sessions will always > have the same path from source to sink. > > This patch is removing the automatic association between path and > tracers. The building of a path and enablement of the components > in the path are decoupled, allowing for the association of a path > with a session rather than a tracer. This patch introduces a use-after-free/double kfree() if the sink is disabled after the source. With this command sequence: # echo 1 > /sys/bus/coresight/devices/54162000.etb/enable_sink # echo 1 > /sys/bus/coresight/devices/5414c000.ptm/enable_source ... # echo 0 > /sys/bus/coresight/devices/54162000.etb/enable_sink # echo 0 > /sys/bus/coresight/devices/5414c000.ptm/enable_source Before these patches, we get these messages while disabling: [ 165.822326] coresight-etm3x 5414c000.ptm: ETM tracing disabled [ 165.828491] coresight 5414c000.ptm: releasing path(s) failed After these patches, we get this (with SLUB debugging enabled): ============================================================================= BUG kmalloc-512 (Not tainted): Invalid object pointer 0xed60e164 ----------------------------------------------------------------------------- Disabling lock debugging due to kernel taint INFO: Slab 0xeebac180 objects=23 used=23 fp=0x (null) flags=0x4081 CPU: 0 PID: 856 Comm: sh Tainted: G B 4.4.0-rc5-00224-ge461459-dirty #168 Hardware name: Generic OMAP4 (Flattened Device Tree) Backtrace: [] (dump_backtrace) from [] (show_stack+0x18/0x1c) r7:00000001 r6:eebac180 r5:c07ae71c r4:00000000 [] (show_stack) from [] (dump_stack+0x98/0xc0) [] (dump_stack) from [] (slab_err+0x78/0x80) r5:ee0013c0 r4:eebac180 [] (slab_err) from [] (free_debug_processing+0x234/0x34c) r3:ed60e164 r2:c068d484 r5:ee0013c0 r4:ed60e164 [] (free_debug_processing) from [] (__slab_free+0x29c/0x428) r10:ee0013c0 r9:00000000 r8:20000013 r7:c041a5f4 r6:ed60e164 r5:00010d00 r4:eebac180 [] (__slab_free) from [] (kfree+0x2dc/0x2f4) r10:eda29f80 r9:00000000 r8:20000013 r7:c041a5f4 r6:ed60e164 r5:eebac180 r4:ee0013c0 [] (kfree) from [] (etm_disable+0xf8/0x148) r10:eda29f80 r9:00000000 r8:ed7ba500 r7:00000000 r6:ed60e120 r5:00000001 r4:ed60e110 [] (etm_disable) from [] (coresight_disable+0xbc/0x100) r7:00000000 r6:c0771150 r5:c076c900 r4:ed662600 [] (coresight_disable) from [] (enable_source_store+0x48/0x68) r9:ed67ec8c r8:ed7d7900 r7:00000000 r6:ed7d7900 r5:00000002 r4:ed662620 [] (enable_source_store) from [] (dev_attr_store+0x20/0x2c) r5:ed67ec80 r4:c0415ea8 [] (dev_attr_store) from [] (sysfs_kf_write+0x50/0x54) r5:ed67ec80 r4:c030b35c [] (sysfs_kf_write) from [] (kernfs_fop_write+0xc4/0x1c0) r7:00000000 r6:00000000 r5:00000002 r4:ed67ec80 [] (kernfs_fop_write) from [] (__vfs_write+0x34/0xe4) r10:00000000 r9:eda28000 r8:c0010964 r7:eda29f80 r6:00000002 r5:c01d4ad4 r4:ed811180 [] (__vfs_write) from [] (vfs_write+0x98/0x174) r9:eda28000 r8:c0010964 r7:eda29f80 r6:000a9e40 r5:00000002 r4:ed811180 [] (vfs_write) from [] (SyS_write+0x4c/0xa8) r8:c0010964 r7:00000002 r6:000a9e40 r5:ed811180 r4:ed811180 [] (SyS_write) from [] (ret_fast_syscall+0x0/0x1c) r7:00000004 r6:00000001 r5:000a9e40 r4:00000002 FIX kmalloc-512: Object at 0xed60e164 not freed