linux-kernel - [PATCH] binfmt_elf: Fix corner case kfree of uninitialized data

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Message-ID: <20121016104757.27601.56082.stgit@localhost.localdomain>
Date:	Tue, 16 Oct 2012 11:48:04 +0100
From:	Alan Cox <alan@...rguk.ukuu.org.uk>
To:	linux-kernel@...r.kernel.org
Subject: [PATCH] binfmt_elf: Fix corner case kfree of uninitialized data

From: Alan Cox <alan@...ux.intel.com>

If elf_core_dump is called and fill_note_info fails in the kmalloc then
it returns 0 but has not yet initialised all the needed fields. As a result
we do a kfree(randomness) after correctly skipping the thread data.

Signed-off-by: Alan Cox <alan@...ux.intel.com>
---

 fs/binfmt_elf.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index fbd9f60..5c07218 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1600,8 +1600,10 @@ static int fill_note_info(struct elfhdr *elf, int phdrs,
 	info->thread = NULL;
 
 	psinfo = kmalloc(sizeof(*psinfo), GFP_KERNEL);
-	if (psinfo == NULL)
+	if (psinfo == NULL) {
+		info->psinfo.data = NULL;	/* So we don't free this wrongly */
 		return 0;
+        }
 
 	fill_note(&info->psinfo, "CORE", NT_PRPSINFO, sizeof(*psinfo), psinfo);
 

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