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Subjectmmc: core: fix possible use after free of host
In the function mmc_alloc_host, the function put_device is called to
release allocated resources when mmc_gpio_alloc fails. Finally, the
function pointed by host->class_dev.class->dev_release (i.e.,
mmc_host_classdev_release) is used to release resources including the
host structure. However, after put_device, host is used and released
again. Resulting in a use-after-free bug.

Fixes: 1ed21719448("mmc: core: fix error path in mmc_host_alloc")
Signed-off-by: Pan Bian <>
drivers/mmc/core/host.c | 2 --
1 file changed, 2 deletions(-)

diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
index 3a4402a..f8ac567 100644
--- a/drivers/mmc/core/host.c
+++ b/drivers/mmc/core/host.c
@@ -429,8 +429,6 @@ struct mmc_host *mmc_alloc_host(int extra, struct device *dev)

if (mmc_gpio_alloc(host)) {
- ida_simple_remove(&mmc_host_ida, host->index);
- kfree(host);
return NULL;


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