linux-kernel - [PATCH] crypto: iaa - Fix potential use after free bug

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Message-ID: <e049271f-41f2-4d04-ac69-80186f2eecd9@stanley.mountain>
Date: Wed, 24 Jul 2024 11:09:43 -0500
From: Dan Carpenter <dan.carpenter@...aro.org>
To: Tom Zanussi <tom.zanussi@...ux.intel.com>
Cc: Herbert Xu <herbert@...dor.apana.org.au>,
	"David S. Miller" <davem@...emloft.net>,
	linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: [PATCH] crypto: iaa - Fix potential use after free bug

The free_device_compression_mode(iaa_device, device_mode) function frees
"device_mode" but it iss passed to iaa_compression_modes[i]->free() a few
lines later resulting in a use after free.

The good news is that, so far as I can tell, nothing implements the
->free() function and the use after free happens in dead code.  But, with
this fix, when something does implement it, we'll be ready.  :)

Fixes: b190447e0fa3 ("crypto: iaa - Add compression mode management along with fixed mode")
Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>
---
 drivers/crypto/intel/iaa/iaa_crypto_main.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/crypto/intel/iaa/iaa_crypto_main.c b/drivers/crypto/intel/iaa/iaa_crypto_main.c
index e810d286ee8c..237f87000070 100644
--- a/drivers/crypto/intel/iaa/iaa_crypto_main.c
+++ b/drivers/crypto/intel/iaa/iaa_crypto_main.c
@@ -495,10 +495,10 @@ static void remove_device_compression_modes(struct iaa_device *iaa_device)
 		if (!device_mode)
 			continue;
 
-		free_device_compression_mode(iaa_device, device_mode);
-		iaa_device->compression_modes[i] = NULL;
 		if (iaa_compression_modes[i]->free)
 			iaa_compression_modes[i]->free(device_mode);
+		free_device_compression_mode(iaa_device, device_mode);
+		iaa_device->compression_modes[i] = NULL;
 	}
 }
 
-- 
2.43.0