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| author | Alan Stern <stern@rowland.harvard.edu> | 2026-02-18 06:10:32 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2026-03-25 13:05:49 +0300 |
| commit | 659c0c7d50a4b0f6aa197c4c098cfd91daf63862 (patch) | |
| tree | 039c43ec5bfb0d816783667505f4f23a8e149067 /include | |
| parent | 39bd4097292fd8564cf2cfba9356f8ab11e38d12 (diff) | |
| download | linux-659c0c7d50a4b0f6aa197c4c098cfd91daf63862.tar.xz | |
USB: core: Limit the length of unkillable synchronous timeouts
commit 1015c27a5e1a63efae2b18a9901494474b4d1dc3 upstream.
The usb_control_msg(), usb_bulk_msg(), and usb_interrupt_msg() APIs in
usbcore allow unlimited timeout durations. And since they use
uninterruptible waits, this leaves open the possibility of hanging a
task for an indefinitely long time, with no way to kill it short of
unplugging the target device.
To prevent this sort of problem, enforce a maximum limit on the length
of these unkillable timeouts. The limit chosen here, somewhat
arbitrarily, is 60 seconds. On many systems (although not all) this
is short enough to avoid triggering the kernel's hung-task detector.
In addition, clear up the ambiguity of negative timeout values by
treating them the same as 0, i.e., using the maximum allowed timeout.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Link: https://lore.kernel.org/linux-usb/3acfe838-6334-4f6d-be7c-4bb01704b33d@rowland.harvard.edu/
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
CC: stable@vger.kernel.org
Link: https://patch.msgid.link/15fc9773-a007-47b0-a703-df89a8cf83dd@rowland.harvard.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/usb.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/include/linux/usb.h b/include/linux/usb.h index a3261427d6e0..6e6e32067148 100644 --- a/include/linux/usb.h +++ b/include/linux/usb.h @@ -1843,6 +1843,9 @@ void usb_buffer_unmap_sg(const struct usb_device *dev, int is_in, * SYNCHRONOUS CALL SUPPORT * *-------------------------------------------------------------------*/ +/* Maximum value allowed for timeout in synchronous routines below */ +#define USB_MAX_SYNCHRONOUS_TIMEOUT 60000 /* ms */ + extern int usb_control_msg(struct usb_device *dev, unsigned int pipe, __u8 request, __u8 requesttype, __u16 value, __u16 index, void *data, __u16 size, int timeout); |