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Thu, 17 Oct 2024 04:44:54 -0700 (PDT) Received: from localhost.localdomain ([4.15.194.220]) by smtp.gmail.com with ESMTPSA id af79cd13be357-7b1540f9075sm14070185a.78.2024.10.17.04.44.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 17 Oct 2024 04:44:54 -0700 (PDT) From: Vimal Agrawal X-Google-Original-From: Vimal Agrawal To: linux-kernel@vger.kernel.org, gregkh@linuxfoundation.org, arnd@arndb.de, quic_jjohnson@quicinc.com, dan.carpenter@linaro.org Cc: avimalin@gmail.com, vimal.agrawal@sophos.com, stable@vger.kernel.org Subject: [PATCH v3 1/2] misc: misc_minor_alloc to use ida for all dynamic/misc dynamic minors Date: Thu, 17 Oct 2024 11:43:29 +0000 Message-Id: <20241017114329.22351-2-vimal.agrawal@sophos.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20241017114329.22351-1-vimal.agrawal@sophos.com> References: <20241017114329.22351-1-vimal.agrawal@sophos.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: misc_minor_alloc was allocating id using ida for minor only in case of MISC_DYNAMIC_MINOR but misc_minor_free was always freeing ids using ida_free causing a mismatch and following warn: > > WARNING: CPU: 0 PID: 159 at lib/idr.c:525 ida_free+0x3e0/0x41f > > ida_free called for id=127 which is not allocated. > > <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< ... > > [<60941eb4>] ida_free+0x3e0/0x41f > > [<605ac993>] misc_minor_free+0x3e/0xbc > > [<605acb82>] misc_deregister+0x171/0x1b3 misc_minor_alloc is changed to allocate id from ida for all minors falling in the range of dynamic/ misc dynamic minors Fixes: ab760791c0cf ("char: misc: Increase the maximum number of dynamic misc devices to 1048448") Signed-off-by: Vimal Agrawal Cc: stable@vger.kernel.org --- v2: Added Fixes: added missed case for static minor in misc_minor_alloc v3: removed kunit changes as that will be added as second patch in this two patch series drivers/char/misc.c | 35 ++++++++++++++++++++++++++++------- 1 file changed, 28 insertions(+), 7 deletions(-) diff --git a/drivers/char/misc.c b/drivers/char/misc.c index 541edc26ec89..9d0cd3459b4f 100644 --- a/drivers/char/misc.c +++ b/drivers/char/misc.c @@ -63,16 +63,30 @@ static DEFINE_MUTEX(misc_mtx); #define DYNAMIC_MINORS 128 /* like dynamic majors */ static DEFINE_IDA(misc_minors_ida); -static int misc_minor_alloc(void) +static int misc_minor_alloc(int minor) { int ret = 0; - ret = ida_alloc_max(&misc_minors_ida, DYNAMIC_MINORS - 1, GFP_KERNEL); - if (ret >= 0) { - ret = DYNAMIC_MINORS - ret - 1; - } else { - ret = ida_alloc_range(&misc_minors_ida, MISC_DYNAMIC_MINOR + 1, + if (minor == MISC_DYNAMIC_MINOR) { + /* allocate free id */ + ret = ida_alloc_max(&misc_minors_ida, DYNAMIC_MINORS - 1, GFP_KERNEL); + if (ret >= 0) { + ret = DYNAMIC_MINORS - ret - 1; + } else { + ret = ida_alloc_range(&misc_minors_ida, MISC_DYNAMIC_MINOR + 1, MINORMASK, GFP_KERNEL); + } + } else { + /* specific minor, check if it is in dynamic or misc dynamic range */ + if (minor < DYNAMIC_MINORS) { + minor = DYNAMIC_MINORS - minor - 1; + ret = ida_alloc_range(&misc_minors_ida, minor, minor, GFP_KERNEL); + } else if (minor > MISC_DYNAMIC_MINOR) { + ret = ida_alloc_range(&misc_minors_ida, minor, minor, GFP_KERNEL); + } else { + /* case of non-dynamic minors, no need to allocate id */ + ret = 0; + } } return ret; } @@ -219,7 +233,7 @@ int misc_register(struct miscdevice *misc) mutex_lock(&misc_mtx); if (is_dynamic) { - int i = misc_minor_alloc(); + int i = misc_minor_alloc(misc->minor); if (i < 0) { err = -EBUSY; @@ -228,6 +242,7 @@ int misc_register(struct miscdevice *misc) misc->minor = i; } else { struct miscdevice *c; + int i; list_for_each_entry(c, &misc_list, list) { if (c->minor == misc->minor) { @@ -235,6 +250,12 @@ int misc_register(struct miscdevice *misc) goto out; } } + + i = misc_minor_alloc(misc->minor); + if (i < 0) { + err = -EBUSY; + goto out; + } } dev = MKDEV(MISC_MAJOR, misc->minor); -- 2.17.1