kernel/linux.git/drivers/usb/gadget/function/f_printer.c, branch v6.6.149

usb: gadget: printer: fix infinite loop in printer_read()

2026-08-03T09:15:16+00:00

commit c2e819be6a5c7f34344926b4bd7e3dfca58cf48a upstream. printer_read() uses the same variable for the requested copy size and the number of bytes actually copied to user space. copy_to_user() returns the number of bytes not copied, so when it fails to copy anything, the computed copied length becomes zero. In that case len, buf, current_rx_bytes and current_rx_buf are left unchanged. If RX data is available and the user buffer remains unwritable, the read loop can repeat indefinitely. Track the copied length separately and return -EFAULT, or the number of bytes already copied, if an iteration makes no progress. Fixes: b185f01a9ab7 ("usb: gadget: printer: factor out f_printer") Cc: stable Reviewed-by: Peter Chen Signed-off-by: Melbin K Mathew Link: https://patch.msgid.link/20260709205622.55700-1-mlbnkm1@gmail.com Signed-off-by: Greg Kroah-Hartman

usb: gadget: f_printer: take kref only for successful open

2026-07-24T14:02:50+00:00

commit 30adce93d5c4a5a1ec29d9249e3fdfcc391d406b upstream. printer_open() returns -EBUSY when the character device is already open, but it increments dev->kref regardless of the return value. VFS does not call ->release() for a failed open, so every rejected second open permanently leaks one reference. Move kref_get() into the successful-open branch. Fixes: e8d5f92b8d30 ("usb: gadget: function: printer: fix use-after-free in __lock_acquire") Cc: stable Signed-off-by: Xu Rao Link: https://patch.msgid.link/80295742B820DA9B+20260626064617.4090626-1-raoxu@uniontech.com Signed-off-by: Greg Kroah-Hartman

usb: gadget: printer: fix races against disable

2024-07-05T07:33:58+00:00

commit e587a7633dfee8987a999cf253f7c52a8e09276c upstream. printer_read() and printer_write() guard against the race against disable() by checking the dev->interface flag, which in turn is guarded by a spinlock. These functions, however, drop the lock on multiple occasions. This means that the test has to be redone after reacquiring the lock and before doing IO. Add the tests. This also addresses CVE-2024-25741 Fixes: 7f2ca14d2f9b9 ("usb: gadget: function: printer: Interface is disabled and returns error") Cc: stable Signed-off-by: Oliver Neukum Link: https://lore.kernel.org/r/20240620114039.5767-1-oneukum@suse.com Signed-off-by: Greg Kroah-Hartman

usb: gadget: printer: SS+ support

2024-07-05T07:33:58+00:00

commit fd80731e5e9d1402cb2f85022a6abf9b1982ec5f upstream. We need to treat super speed plus as super speed, not the default, which is full speed. Signed-off-by: Oliver Neukum Cc: stable Link: https://lore.kernel.org/r/20240620093800.28901-1-oneukum@suse.com Signed-off-by: Greg Kroah-Hartman

usb: gadget: function: Remove usage of the deprecated ida_simple_xx() API

2024-06-27T11:49:04+00:00

[ Upstream commit 920e7522e3bab5ebc2fb0cc1a034f4470c87fa97 ] ida_alloc() and ida_free() should be preferred to the deprecated ida_simple_get() and ida_simple_remove(). Note that the upper limit of ida_simple_get() is exclusive, but the one of ida_alloc_max() is inclusive. So a -1 has been added when needed. Signed-off-by: Christophe JAILLET Link: https://lore.kernel.org/r/7cd361e2b377a5373968fa7deee4169229992a1e.1713107386.git.christophe.jaillet@wanadoo.fr Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin

USB: gadget: f_printer: make usb_gadget_class a static const structure

2023-06-20T14:20:47+00:00

Now that the driver core allows for struct class to be in read-only memory, move the usb_gadget_class structure to be declared at build time placing it into read-only memory, instead of having to be dynamically allocated at load time. Suggested-by: Greg Kroah-Hartman Signed-off-by: Ivan Orlov Link: https://lore.kernel.org/r/20230620094412.508580-10-gregkh@linuxfoundation.org Signed-off-by: Greg Kroah-Hartman

usb: gadget: function: printer: Replace strlcpy with strscpy

2023-06-19T13:34:40+00:00

strlcpy() reads the entire source buffer first. This read may exceed the destination size limit. This is both inefficient and can lead to linear read overflows if a source string is not NUL-terminated [1]. In an effort to remove strlcpy() completely [2], replace strlcpy() here with strscpy(). Direct replacement is safe here since return value of -errno is used to check for truncation instead of PAGE_SIZE. [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy [2] https://github.com/KSPP/linux/issues/89 Signed-off-by: Azeem Shaikh Link: https://lore.kernel.org/r/20230615180318.400639-1-azeemshaikh38@gmail.com Signed-off-by: Greg Kroah-Hartman

driver core: class: remove module * from class_create()

2023-03-17T14:16:33+00:00

The module pointer in class_create() never actually did anything, and it shouldn't have been requred to be set as a parameter even if it did something. So just remove it and fix up all callers of the function in the kernel tree at the same time. Cc: "Rafael J. Wysocki" Acked-by: Benjamin Tissoires Link: https://lore.kernel.org/r/20230313181843.1207845-4-gregkh@linuxfoundation.org Signed-off-by: Greg Kroah-Hartman

usb: gadget: function: Simplify diagnostic messaging in printer

2022-11-29T07:56:09+00:00

Don't issue messages which can be easily achieved with ftrace. In case of printer_open() the return code is propagated to other layers so the user will know about -EBUSY anyway. Signed-off-by: Andrzej Pietrasiewicz Link: https://lore.kernel.org/r/20221123110746.59611-1-andrzej.p@collabora.com Signed-off-by: Greg Kroah-Hartman

usb: gadget: function: fix dangling pnp_string in f_printer.c

2022-09-22T13:52:29+00:00

When opts->pnp_string is changed with configfs, new memory is allocated for the string. It does not, however, update dev->pnp_string, even though the memory is freed. When rquesting the string, the host then gets old or corrupted data rather than the new string. The ieee 1284 id string should be allowed to change while the device is connected. The bug was introduced in commit fdc01cc286be ("usb: gadget: printer: Remove pnp_string static buffer"), which changed opts->pnp_string from a char[] to a char*. This patch changes dev->pnp_string from a char* to a char** pointing to opts->pnp_string. Fixes: fdc01cc286be ("usb: gadget: printer: Remove pnp_string static buffer") Signed-off-by: Albert Briscoe Link: https://lore.kernel.org/r/20220911223753.20417-1-albertsbriscoe@gmail.com Signed-off-by: Greg Kroah-Hartman