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Thu, 12 Sep 2024 13:21:28 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id Tbr9E9jq4mZpbQAAD6G6ig (envelope-from ); Thu, 12 Sep 2024 13:21:28 +0000 From: Oliver Neukum To: gregkh@linuxfoundation.org, lee@kernel.org, linux-usb@vger.kernel.org Cc: Oliver Neukum , stable@vger.kernel.org Subject: [PATCH] USB: misc: yurex: fix race between read and write Date: Thu, 12 Sep 2024 15:21:22 +0200 Message-ID: <20240912132126.1034743-1-oneukum@suse.com> X-Mailer: git-send-email 2.45.2 Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Rspamd-Queue-Id: 7904521AEF X-Spam-Level: X-Spamd-Result: default: False [-5.01 / 50.00]; BAYES_HAM(-3.00)[99.99%]; DWL_DNSWL_MED(-2.00)[suse.com:dkim]; MID_CONTAINS_FROM(1.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_MISSING_CHARSET(0.50)[]; R_DKIM_ALLOW(-0.20)[suse.com:s=susede1]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; ARC_NA(0.00)[]; RECEIVED_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:106:10:150:64:167:received]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:97:from]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; MIME_TRACE(0.00)[0:+]; SPAMHAUS_XBL(0.00)[2a07:de40:b281:104:10:150:64:97:from]; FUZZY_BLOCKED(0.00)[rspamd.com]; DKIM_SIGNED(0.00)[suse.com:s=susede1]; RCVD_COUNT_TWO(0.00)[2]; RCVD_TLS_ALL(0.00)[]; DKIM_TRACE(0.00)[suse.com:+]; RCVD_VIA_SMTP_AUTH(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; RCPT_COUNT_FIVE(0.00)[5]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.com:email, suse.com:dkim, suse.com:mid, imap1.dmz-prg2.suse.org:helo, imap1.dmz-prg2.suse.org:rdns] X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Rspamd-Action: no action X-Spam-Score: -5.01 X-Spam-Flag: NO The write code path touches the bbu member in a non atomic manner without taking the spinlock. Fix it. The bug is as old as the driver. Signed-off-by: Oliver Neukum CC: stable@vger.kernel.org --- drivers/usb/misc/yurex.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/drivers/usb/misc/yurex.c b/drivers/usb/misc/yurex.c index 4745a320eae4..4a9859e03f6b 100644 --- a/drivers/usb/misc/yurex.c +++ b/drivers/usb/misc/yurex.c @@ -404,7 +404,6 @@ static ssize_t yurex_read(struct file *file, char __user *buffer, size_t count, struct usb_yurex *dev; int len = 0; char in_buffer[MAX_S64_STRLEN]; - unsigned long flags; dev = file->private_data; @@ -419,9 +418,9 @@ static ssize_t yurex_read(struct file *file, char __user *buffer, size_t count, return -EIO; } - spin_lock_irqsave(&dev->lock, flags); + spin_lock_irq(&dev->lock); scnprintf(in_buffer, MAX_S64_STRLEN, "%lld\n", dev->bbu); - spin_unlock_irqrestore(&dev->lock, flags); + spin_unlock_irq(&dev->lock); mutex_unlock(&dev->io_mutex); return simple_read_from_buffer(buffer, count, ppos, in_buffer, len); @@ -511,8 +510,11 @@ static ssize_t yurex_write(struct file *file, const char __user *user_buffer, __func__, retval); goto error; } - if (set && timeout) + if (set && timeout) { + spin_lock_irq(&dev->lock); dev->bbu = c2; + spin_unlock_irq(&dev->lock); + } return timeout ? count : -EIO; error: