From: trix@redhat.com
To: giovanni.cabiddu@intel.com, herbert@gondor.apana.org.au,
davem@davemloft.net, wojciech.ziemba@intel.com,
karen.xiang@intel.com, bruce.w.allan@intel.com, bo.cui@intel.com,
pingchaox.yang@intel.com
Cc: qat-linux@intel.com, linux-crypto@vger.kernel.org,
linux-kernel@vger.kernel.org, stable@vger.kernel.org,
Tom Rix <trix@redhat.com>
Subject: [PATCH] crypto: qat: fix double free in qat_uclo_create_batch_init_list
Date: Mon, 13 Jul 2020 07:06:34 -0700 [thread overview]
Message-ID: <20200713140634.14730-1-trix@redhat.com> (raw)
From: Tom Rix <trix@redhat.com>
clang static analysis flags this error
qat_uclo.c:297:3: warning: Attempt to free released memory
[unix.Malloc]
kfree(*init_tab_base);
^~~~~~~~~~~~~~~~~~~~~
When input *init_tab_base is null, the function allocates memory for
the head of the list. When there is problem allocating other list
elements the list is unwound and freed. Then a check is made if the
list head was allocated and is also freed.
Keeping track of the what may need to be freed is the variable 'tail_old'.
The unwinding/freeing block is
while (tail_old) {
mem_init = tail_old->next;
kfree(tail_old);
tail_old = mem_init;
}
The problem is that the first element of tail_old is also what was
allocated for the list head
init_header = kzalloc(sizeof(*init_header), GFP_KERNEL);
...
*init_tab_base = init_header;
flag = 1;
}
tail_old = init_header;
So *init_tab_base/init_header are freed twice.
There is another problem.
When the input *init_tab_base is non null the tail_old is calculated by
traveling down the list to first non null entry.
tail_old = init_header;
while (tail_old->next)
tail_old = tail_old->next;
When the unwinding free happens, the last entry of the input list will
be freed.
So the freeing needs a general changed.
If locally allocated the first element of tail_old is freed, else it
is skipped. As a bit of cleanup, reset *init_tab_base if it came in
as null.
Fixes: b4b7e67c917f ("crypto: qat - Intel(R) QAT ucode part of fw loader")
Signed-off-by: Tom Rix <trix@redhat.com>
---
drivers/crypto/qat/qat_common/qat_uclo.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/drivers/crypto/qat/qat_common/qat_uclo.c b/drivers/crypto/qat/qat_common/qat_uclo.c
index 4cc1f436b075..bff759e2f811 100644
--- a/drivers/crypto/qat/qat_common/qat_uclo.c
+++ b/drivers/crypto/qat/qat_common/qat_uclo.c
@@ -288,13 +288,18 @@ static int qat_uclo_create_batch_init_list(struct icp_qat_fw_loader_handle
}
return 0;
out_err:
+ /* Do not free the list head unless we allocated it. */
+ tail_old = tail_old->next;
+ if (flag) {
+ kfree(*init_tab_base);
+ *init_tab_base = NULL;
+ }
+
while (tail_old) {
mem_init = tail_old->next;
kfree(tail_old);
tail_old = mem_init;
}
- if (flag)
- kfree(*init_tab_base);
return -ENOMEM;
}
--
2.18.1
next reply other threads:[~2020-07-13 14:06 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-13 14:06 trix [this message]
2020-07-13 14:19 ` [PATCH] crypto: qat: fix double free in qat_uclo_create_batch_init_list Greg KH
2020-07-23 7:56 ` Herbert Xu
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