(Resending with all recipients, sorry)
On Sat, Aug 20, 2016 at 1:52 AM, Sebastian Andrzej Siewior
<bige...@linutronix.de> wrote:
> A basic rmmod ramoops segfaults. Let's see why.
>
> Since commit 34f0ec82e0a9 ("pstore: Correct the max_dump_cnt clearing of
> ramoops") sets ->max_dump_cnt to zero before looping over ->przs but we
> didn't use it before that either.
>
> And since commit ee1d267423a1 ("pstore: add pstore unregister") we free
> that memory on rmmod.
>
> But even then, we looped until a NULL pointer or ERR. I don't see where
> it is ensured that the last member is NULL. Let's try this instead:
> simply error recovery and free. Clean up in error case where ressouces
> were allocated. And then, in the free path, rely on ->max_dump_cnt in
> the free path.
>
> Cc: Anton Vorontsov <an...@enomsg.org>
> Cc: Colin Cross <ccr...@android.com>
> Cc: Kees Cook <keesc...@chromium.org>
> Cc: Tony Luck <tony.l...@intel.com>
> Signed-off-by: Sebastian Andrzej Siewior <bige...@linutronix.de>
Fwiw,
Acked-by: Namhyung Kim <namhy...@kernel.org>
Thanks,
Namhyung
> ---
>
> Not sure if I miss something obvious or not.
>
> fs/pstore/ram.c | 17 ++++++++++++-----
> 1 file changed, 12 insertions(+), 5 deletions(-)
>
> diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
> index 7a034d62cf8c..2340262a7e97 100644
> --- a/fs/pstore/ram.c
> +++ b/fs/pstore/ram.c
> @@ -377,13 +377,14 @@ static void ramoops_free_przs(struct ramoops_context
> *cxt)
> {
> int i;
>
> - cxt->max_dump_cnt = 0;
> if (!cxt->przs)
> return;
>
> - for (i = 0; !IS_ERR_OR_NULL(cxt->przs[i]); i++)
> + for (i = 0; i < cxt->max_dump_cnt; i++)
> persistent_ram_free(cxt->przs[i]);
> +
> kfree(cxt->przs);
> + cxt->max_dump_cnt = 0;
> }
>
> static int ramoops_init_przs(struct device *dev, struct ramoops_context *cxt,
> @@ -408,7 +409,7 @@ static int ramoops_init_przs(struct device *dev, struct
> ramoops_context *cxt,
> GFP_KERNEL);
> if (!cxt->przs) {
> dev_err(dev, "failed to initialize a prz array for dumps\n");
> - goto fail_prz;
> + goto fail_mem;
> }
>
> for (i = 0; i < cxt->max_dump_cnt; i++) {
> @@ -419,6 +420,11 @@ static int ramoops_init_przs(struct device *dev, struct
> ramoops_context *cxt,
> err = PTR_ERR(cxt->przs[i]);
> dev_err(dev, "failed to request mem region
> (0x%zx@0x%llx): %d\n",
> cxt->record_size, (unsigned long long)*paddr,
> err);
> +
> + while (i > 0) {
> + i--;
> + persistent_ram_free(cxt->przs[i]);
> + }
> goto fail_prz;
> }
> *paddr += cxt->record_size;
> @@ -426,7 +432,9 @@ static int ramoops_init_przs(struct device *dev, struct
> ramoops_context *cxt,
>
> return 0;
> fail_prz:
> - ramoops_free_przs(cxt);
> + kfree(cxt->przs);
> +fail_mem:
> + cxt->max_dump_cnt = 0;
> return err;
> }
>
> @@ -659,7 +667,6 @@ static int ramoops_remove(struct platform_device *pdev)
> struct ramoops_context *cxt = &oops_cxt;
>
> pstore_unregister(&cxt->pstore);
> - cxt->max_dump_cnt = 0;
>
> kfree(cxt->pstore.buf);
> cxt->pstore.bufsize = 0;
> --
> 2.9.3
>
