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authorYves-Alexis Perez <corsac@corsac.net>2016-11-11 11:28:40 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-01-09 08:07:49 +0100
commit656c9abd574bc4be3890cd2d104a422dd93ca3aa (patch)
treee093bcfa6874065fbde634e250a2d82a1112d50b /drivers/base
parent429a533a3d9ac849b4c9c3ceed14aa4282301748 (diff)
firmware: fix usermode helper fallback loading
commit 2e700f8d85975f516ccaad821278c1fe66b2cc98 upstream. When you use the firmware usermode helper fallback with a timeout value set to a value greater than INT_MAX (2147483647) a cast overflow issue causes the timeout value to go negative and breaks all usermode helper loading. This regression was introduced through commit 68ff2a00dbf5 ("firmware_loader: handle timeout via wait_for_completion_interruptible_timeout()") on kernel v4.0. The firmware_class drivers relies on the firmware usermode helper fallback as a mechanism to look for firmware if the direct filesystem search failed only if: a) You've enabled CONFIG_FW_LOADER_USER_HELPER_FALLBACK (not many distros): Then all of these callers will rely on the fallback mechanism in case the firmware is not found through an initial direct filesystem lookup: o request_firmware() o request_firmware_into_buf() o request_firmware_nowait() b) If you've only enabled CONFIG_FW_LOADER_USER_HELPER (most distros): Then only callers using request_firmware_nowait() with the second argument set to false, this explicitly is requesting the UMH firmware fallback to be relied on in case the first filesystem lookup fails. Using Coccinelle SmPL grammar we have identified only two drivers explicitly requesting the UMH firmware fallback mechanism: - drivers/firmware/dell_rbu.c - drivers/leds/leds-lp55xx-common.c Since most distributions only enable CONFIG_FW_LOADER_USER_HELPER the biggest impact of this regression are users of the dell_rbu and leds-lp55xx-common device driver which required the UMH to find their respective needed firmwares. The default timeout for the UMH is set to 60 seconds always, as of commit 68ff2a00dbf5 ("firmware_loader: handle timeout via wait_for_completion_interruptible_timeout()") the timeout was bumped to MAX_JIFFY_OFFSET ((LONG_MAX >> 1)-1). Additionally the MAX_JIFFY_OFFSET value was also used if the timeout was configured by a user to 0. The following works: echo 2147483647 > /sys/class/firmware/timeout But both of the following set the timeout to MAX_JIFFY_OFFSET even if we display 0 back to userspace: echo 2147483648 > /sys/class/firmware/timeout cat /sys/class/firmware/timeout 0 echo 0> /sys/class/firmware/timeout cat /sys/class/firmware/timeout 0 A max value of INT_MAX (2147483647) seconds is therefore implicit due to the another cast with simple_strtol(). This fixes the secondary cast (the first one is simple_strtol() but its an issue only by forcing an implicit limit) by re-using the timeout variable and only setting retval in appropriate cases. Lastly worth noting systemd had ripped out the UMH firmware fallback mechanism from udev since udev 2014 via commit be2ea723b1d023b3d ("udev: remove userspace firmware loading support"), so as of systemd v217. Signed-off-by: Yves-Alexis Perez <corsac@corsac.net> Fixes: 68ff2a00dbf5 "firmware_loader: handle timeout via wait_for_completion_interruptible_timeout()" Cc: Luis R. Rodriguez <mcgrof@kernel.org> Cc: Ming Lei <ming.lei@canonical.com> Cc: Bjorn Andersson <bjorn.andersson@linaro.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Acked-by: Luis R. Rodriguez <mcgrof@kernel.org> Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org> [mcgrof@kernel.org: gave commit log a whole lot of love] Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/base')
-rw-r--r--drivers/base/firmware_class.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index 8524450e75bd..ccfd268148a8 100644
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -942,13 +942,14 @@ static int _request_firmware_load(struct firmware_priv *fw_priv,
timeout = MAX_JIFFY_OFFSET;
}
- retval = wait_for_completion_interruptible_timeout(&buf->completion,
+ timeout = wait_for_completion_interruptible_timeout(&buf->completion,
timeout);
- if (retval == -ERESTARTSYS || !retval) {
+ if (timeout == -ERESTARTSYS || !timeout) {
+ retval = timeout;
mutex_lock(&fw_lock);
fw_load_abort(fw_priv);
mutex_unlock(&fw_lock);
- } else if (retval > 0) {
+ } else if (timeout > 0) {
retval = 0;
}