linux-kernel - Re: drivers/edac/ move a kfree() to after last use

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Date:	Mon, 21 Dec 2009 16:18:19 +0100
From:	Borislav Petkov <borislav.petkov@....com>
To:	Darren Jenkins <darrenrjenkins@...il.com>
CC:	Kernel Janitors <kernel-janitors@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	dougthompson@...ssion.com, bluesmoke-devel@...ts.sourceforge.net
Subject: Re: drivers/edac/ move a kfree() to after last use

On Mon, Dec 21, 2009 at 03:38:26PM +1100, Darren Jenkins wrote:
> 
> Move a kfree() below the last use of the memory
> 
> Coverity CID: 13142
> 
> Signed-off-by: Darren Jenkins <darrenrjenkins@...il.com>

Thanks for catching that. Here's a better version that does all the
freeing at the end of the function.

--
From: Borislav Petkov <borislav.petkov@....com>
Date: Mon, 21 Dec 2009 15:15:59 +0100
Subject: [PATCH] amd64_edac: fix driver instance freeing

Fix use-after-free errors by pushing all memory-freeing calls to the end
of amd64_remove_one_instance().

Reported-by: Darren Jenkins <darrenrjenkins@...il.com>
Signed-off-by: Borislav Petkov <borislav.petkov@....com>
---
 drivers/edac/amd64_edac.c |    9 ++++-----
 1 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/edac/amd64_edac.c b/drivers/edac/amd64_edac.c
index 784cc5a..fb0d36b 100644
--- a/drivers/edac/amd64_edac.c
+++ b/drivers/edac/amd64_edac.c
@@ -2929,16 +2929,15 @@ static void __devexit amd64_remove_one_instance(struct pci_dev *pdev)
 
 	amd64_free_mc_sibling_devices(pvt);
 
-	kfree(pvt);
-	mci->pvt_info = NULL;
-
-	mci_lookup[pvt->mc_node_id] = NULL;
-
 	/* unregister from EDAC MCE */
 	amd_report_gart_errors(false);
 	amd_unregister_ecc_decoder(amd64_decode_bus_error);
 
 	/* Free the EDAC CORE resources */
+	mci->pvt_info = NULL;
+	mci_lookup[pvt->mc_node_id] = NULL;
+
+	kfree(pvt);
 	edac_mc_free(mci);
 }
 
-- 
1.6.5.4


-- 
Regards/Gruss,
Boris.

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