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staging: gasket: core: protect against races during unregister

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Keep mutex held across the unregistration operation, until the
driver_desc field of the global table is removed, to prevent a
concurrent accessor from looking up the driver_desc while
gasket_unregister_device() is in the processing of removing it.

Reported-by: Guenter Roeck <groeck@chromium.org>
Signed-off-by: Todd Poynor <toddpoynor@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Todd Poynor
2018-08-05 13:07:47 -07:00
committed by Alex Van Damme
parent 9117159d16
commit 52f647e62e
1 changed files with 1 additions and 2 deletions
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3
gasket_core.c
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@@ -1765,9 +1765,9 @@ void gasket_unregister_device(const struct gasket_driver_desc *driver_desc)
break; break;
} }
} }
mutex_unlock(&g_mutex);
if (!internal_desc) { if (!internal_desc) {
mutex_unlock(&g_mutex);
pr_err("request to unregister unknown desc: %s, %d:%d\n", pr_err("request to unregister unknown desc: %s, %d:%d\n",
driver_desc->name, driver_desc->major, driver_desc->name, driver_desc->major,
driver_desc->minor); driver_desc->minor);
@@ -1780,7 +1780,6 @@ void gasket_unregister_device(const struct gasket_driver_desc *driver_desc)
class_destroy(internal_desc->class); class_destroy(internal_desc->class);
/* Finally, effectively "remove" the driver. */ /* Finally, effectively "remove" the driver. */
mutex_lock(&g_mutex);
g_descs[desc_idx].driver_desc = NULL; g_descs[desc_idx].driver_desc = NULL;
mutex_unlock(&g_mutex); mutex_unlock(&g_mutex);