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authorWilliam A. Kennington III <wak@google.com>2021-04-07 02:55:27 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2021-06-03 08:22:06 +0200
commit62bb2c7f2411a0045c24831f11ecacfc35610815 (patch)
treee1b7f422bc0a287f263b794d3388446284cc1862 /drivers/spi
parent200dbfcad8011e50c3cec269ed7b980836eeb1fa (diff)
spi: Fix use-after-free with devm_spi_alloc_*
commit 794aaf01444d4e765e2b067cba01cc69c1c68ed9 upstream. We can't rely on the contents of the devres list during spi_unregister_controller(), as the list is already torn down at the time we perform devres_find() for devm_spi_release_controller. This causes devices registered with devm_spi_alloc_{master,slave}() to be mistakenly identified as legacy, non-devm managed devices and have their reference counters decremented below 0. ------------[ cut here ]------------ WARNING: CPU: 1 PID: 660 at lib/refcount.c:28 refcount_warn_saturate+0x108/0x174 [<b0396f04>] (refcount_warn_saturate) from [<b03c56a4>] (kobject_put+0x90/0x98) [<b03c5614>] (kobject_put) from [<b0447b4c>] (put_device+0x20/0x24) r4:b6700140 [<b0447b2c>] (put_device) from [<b07515e8>] (devm_spi_release_controller+0x3c/0x40) [<b07515ac>] (devm_spi_release_controller) from [<b045343c>] (release_nodes+0x84/0xc4) r5:b6700180 r4:b6700100 [<b04533b8>] (release_nodes) from [<b0454160>] (devres_release_all+0x5c/0x60) r8:b1638c54 r7:b117ad94 r6:b1638c10 r5:b117ad94 r4:b163dc10 [<b0454104>] (devres_release_all) from [<b044e41c>] (__device_release_driver+0x144/0x1ec) r5:b117ad94 r4:b163dc10 [<b044e2d8>] (__device_release_driver) from [<b044f70c>] (device_driver_detach+0x84/0xa0) r9:00000000 r8:00000000 r7:b117ad94 r6:b163dc54 r5:b1638c10 r4:b163dc10 [<b044f688>] (device_driver_detach) from [<b044d274>] (unbind_store+0xe4/0xf8) Instead, determine the devm allocation state as a flag on the controller which is guaranteed to be stable during cleanup. Fixes: 5e844cc37a5c ("spi: Introduce device-managed SPI controller allocation") Signed-off-by: William A. Kennington III <wak@google.com> Link: https://lore.kernel.org/r/20210407095527.2771582-1-wak@google.com Signed-off-by: Mark Brown <broonie@kernel.org> [lukas: backport to v4.4.270] Signed-off-by: Lukas Wunner <lukas@wunner.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/spi')
-rw-r--r--drivers/spi/spi.c9
1 files changed, 2 insertions, 7 deletions
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index e85feee750e3..f743b95d5171 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -1762,6 +1762,7 @@ struct spi_master *devm_spi_alloc_master(struct device *dev, unsigned int size)
master = spi_alloc_master(dev, size);
if (master) {
+ master->devm_allocated = true;
*ptr = master;
devres_add(dev, ptr);
} else {
@@ -1951,11 +1952,6 @@ int devm_spi_register_master(struct device *dev, struct spi_master *master)
}
EXPORT_SYMBOL_GPL(devm_spi_register_master);
-static int devm_spi_match_master(struct device *dev, void *res, void *master)
-{
- return *(struct spi_master **)res == master;
-}
-
static int __unregister(struct device *dev, void *null)
{
spi_unregister_device(to_spi_device(dev));
@@ -1994,8 +1990,7 @@ void spi_unregister_master(struct spi_master *master)
/* Release the last reference on the master if its driver
* has not yet been converted to devm_spi_alloc_master().
*/
- if (!devres_find(master->dev.parent, devm_spi_release_master,
- devm_spi_match_master, master))
+ if (!master->devm_allocated)
put_device(&master->dev);
if (IS_ENABLED(CONFIG_SPI_DYNAMIC))