From: Alexander Wetzel <Alexander@wetzel-home.de> To: dgilbert@interlog.com Cc: gregkh@linuxfoundation.org, sachinp@linux.ibm.com, Alexander@wetzel-home.de, bvanassche@acm.org, linux-scsi@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, martin.petersen@oracle.com, stable@vger.kernel.org Subject: [PATCH v2] scsi: sg: Avoid race in error handling & drop bogus warn Date: Mon, 1 Apr 2024 12:03:17 +0200 [thread overview] Message-ID: <20240401100317.5395-1-Alexander@wetzel-home.de> (raw) In-Reply-To: <81266270-42F4-48F9-9139-8F0C3F0A6553@linux.ibm.com> commit 27f58c04a8f4 ("scsi: sg: Avoid sg device teardown race") introduced an incorrect WARN_ON_ONCE() and missed a sequence where sg_device_destroy() was used after scsi_device_put(). sg_device_destroy() is accessing the parent scsi_device request_queue which will already be set to NULL when the preceding call to scsi_device_put() removed the last reference to the parent scsi_device. Drop the incorrect WARN_ON_ONCE() - allowing more than one concurrent access to the sg device - and make sure sg_device_destroy() is not used after scsi_device_put() in the error handling. Link: https://lore.kernel.org/all/5375B275-D137-4D5F-BE25-6AF8ACAE41EF@linux.ibm.com Fixes: 27f58c04a8f4 ("scsi: sg: Avoid sg device teardown race") Cc: stable@vger.kernel.org Signed-off-by: Alexander Wetzel <Alexander@wetzel-home.de> --- Changes compared to V1: fixed commit message The WARN_ON_ONCE() was kind of stupid to add: We get add reference for each sg_open(). So opening a second session and then closing either one will trigger the warning... Nothing to warn about here. Alexander --- drivers/scsi/sg.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c index 386981c6976a..833c9277419b 100644 --- a/drivers/scsi/sg.c +++ b/drivers/scsi/sg.c @@ -372,8 +372,9 @@ sg_open(struct inode *inode, struct file *filp) error_out: scsi_autopm_put_device(sdp->device); sdp_put: + kref_put(&sdp->d_ref, sg_device_destroy); scsi_device_put(sdp->device); - goto sg_put; + return retval; } /* Release resources associated with a successful sg_open() @@ -2233,7 +2234,6 @@ sg_remove_sfp_usercontext(struct work_struct *work) "sg_remove_sfp: sfp=0x%p\n", sfp)); kfree(sfp); - WARN_ON_ONCE(kref_read(&sdp->d_ref) != 1); kref_put(&sdp->d_ref, sg_device_destroy); scsi_device_put(device); module_put(THIS_MODULE); -- 2.44.0
WARNING: multiple messages have this Message-ID (diff)
From: Alexander Wetzel <Alexander@wetzel-home.de> To: dgilbert@interlog.com Cc: bvanassche@acm.org, linux-scsi@vger.kernel.org, gregkh@linuxfoundation.org, stable@vger.kernel.org, Alexander@wetzel-home.de, sachinp@linux.ibm.com, martin.petersen@oracle.com, linuxppc-dev@lists.ozlabs.org Subject: [PATCH v2] scsi: sg: Avoid race in error handling & drop bogus warn Date: Mon, 1 Apr 2024 12:03:17 +0200 [thread overview] Message-ID: <20240401100317.5395-1-Alexander@wetzel-home.de> (raw) In-Reply-To: <81266270-42F4-48F9-9139-8F0C3F0A6553@linux.ibm.com> commit 27f58c04a8f4 ("scsi: sg: Avoid sg device teardown race") introduced an incorrect WARN_ON_ONCE() and missed a sequence where sg_device_destroy() was used after scsi_device_put(). sg_device_destroy() is accessing the parent scsi_device request_queue which will already be set to NULL when the preceding call to scsi_device_put() removed the last reference to the parent scsi_device. Drop the incorrect WARN_ON_ONCE() - allowing more than one concurrent access to the sg device - and make sure sg_device_destroy() is not used after scsi_device_put() in the error handling. Link: https://lore.kernel.org/all/5375B275-D137-4D5F-BE25-6AF8ACAE41EF@linux.ibm.com Fixes: 27f58c04a8f4 ("scsi: sg: Avoid sg device teardown race") Cc: stable@vger.kernel.org Signed-off-by: Alexander Wetzel <Alexander@wetzel-home.de> --- Changes compared to V1: fixed commit message The WARN_ON_ONCE() was kind of stupid to add: We get add reference for each sg_open(). So opening a second session and then closing either one will trigger the warning... Nothing to warn about here. Alexander --- drivers/scsi/sg.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c index 386981c6976a..833c9277419b 100644 --- a/drivers/scsi/sg.c +++ b/drivers/scsi/sg.c @@ -372,8 +372,9 @@ sg_open(struct inode *inode, struct file *filp) error_out: scsi_autopm_put_device(sdp->device); sdp_put: + kref_put(&sdp->d_ref, sg_device_destroy); scsi_device_put(sdp->device); - goto sg_put; + return retval; } /* Release resources associated with a successful sg_open() @@ -2233,7 +2234,6 @@ sg_remove_sfp_usercontext(struct work_struct *work) "sg_remove_sfp: sfp=0x%p\n", sfp)); kfree(sfp); - WARN_ON_ONCE(kref_read(&sdp->d_ref) != 1); kref_put(&sdp->d_ref, sg_device_destroy); scsi_device_put(device); module_put(THIS_MODULE); -- 2.44.0
next prev parent reply other threads:[~2024-04-01 10:03 UTC|newest] Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top 2024-03-29 9:08 [powerpc] WARN at drivers/scsi/sg.c:2236 (sg_remove_sfp_usercontext) Sachin Sant 2024-03-29 9:08 ` Sachin Sant 2024-03-29 11:10 ` Alexander Wetzel 2024-03-29 11:10 ` Alexander Wetzel 2024-03-29 14:37 ` Sachin Sant 2024-04-01 9:56 ` [PATCH] scsi: sg: Avoid race in error handling & drop bogus warn Alexander Wetzel 2024-04-01 9:56 ` Alexander Wetzel 2024-04-01 10:03 ` Alexander Wetzel [this message] 2024-04-01 10:03 ` [PATCH v2] " Alexander Wetzel 2024-04-01 17:09 ` Bart Van Assche 2024-04-01 17:09 ` Bart Van Assche 2024-04-01 19:01 ` Alexander Wetzel 2024-04-01 19:01 ` Alexander Wetzel 2024-04-01 19:10 ` [PATCH v3] " Alexander Wetzel 2024-04-01 19:10 ` Alexander Wetzel 2024-04-02 6:01 ` Sachin Sant 2024-04-02 6:01 ` Sachin Sant 2024-04-03 23:24 ` Bart Van Assche 2024-04-03 23:24 ` Bart Van Assche 2024-04-04 6:55 ` Alexander Wetzel 2024-04-04 6:55 ` Alexander Wetzel 2024-04-04 16:34 ` Bart Van Assche 2024-04-04 16:34 ` Bart Van Assche 2024-04-04 22:22 ` Martin K. Petersen 2024-04-04 22:22 ` Martin K. Petersen 2024-04-06 1:58 ` Martin K. Petersen 2024-04-06 1:58 ` Martin K. Petersen
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