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SubjectRe: [PATCH] Memory leak in tpm_ascii_bios_measurements_open() fix.
Jesper,

thank you very much for finding this error and for posting a patch
proposal. Since Kylene is not online, I am responding. Please see my
inlines and an alternative patch proposal below.

Jesper Juhl <jesper.juhl@gmail.com> wrote on 07/18/2007 07:11:54 PM:

> Ehlo,
>
> Coverity found a memory leak in tpm_ascii_bios_measurements_open().
>
> If "read_log(log)" fails, then we may leak 'log' and
> 'log->bios_event_log'.
>
> This patch should fix it, but please double check it. I don't know
> this code very well and the patch has only been compile tested.
>
>
> Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
> ---
>
> drivers/char/tpm/tpm_bios.c | 11 ++++++++---
> 1 files changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm_bios.c b/drivers/char/tpm/tpm_bios.c
> index 4eba32b..4b26ce4 100644
> --- a/drivers/char/tpm/tpm_bios.c
> +++ b/drivers/char/tpm/tpm_bios.c
> @@ -427,7 +427,7 @@ static int
> tpm_ascii_bios_measurements_open(struct inode *inode,
> return -ENOMEM;
>
> if ((err = read_log(log)))
> - return err;
> + goto out_free;


log->bios_event_log should not be pointing to allocated memory here
(seems cleaner if read_log cleans its allocated memory in the error case)
---> just free log


>
> /* now register seq file */
> err = seq_open(file, &tpm_ascii_b_measurments_seqops);
> @@ -435,10 +435,15 @@ static int
> tpm_ascii_bios_measurements_open(struct inode *inode,
> seq = file->private_data;
> seq->private = log;
> } else {
> - kfree(log->bios_event_log);
> - kfree(log);
> + goto out_free;
> }
> +
> +out:
> return err;
> +out_free:
> + kfree(log->bios_event_log);
> + kfree(log);
> + goto out;
> }
> const struct file_operations tpm_ascii_bios_measurements_ops = {
>
>

The following patch should be sufficient to fix the problem you discovered:
---
drivers/char/tpm/tpm_bios.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
Index: linux-2.6.22-rc7/drivers/char/tpm/tpm_bios.c
===================================================================
--- linux-2.6.22-rc7.orig/drivers/char/tpm/tpm_bios.c
+++ linux-2.6.22-rc7/drivers/char/tpm/tpm_bios.c
@@ -426,9 +426,10 @@ static int tpm_ascii_bios_measurements_o
if (!log)
return -ENOMEM;

- if ((err = read_log(log)))
+ if ((err = read_log(log))) {
+ kfree(log);
return err;
-
+ }
/* now register seq file */
err = seq_open(file, &tpm_ascii_b_measurments_seqops);
if (!err) {
Do you agree?

Greetings
Reiner

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