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Commit 4407de74 authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Kees Cook
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pstore/ramoops: fixup driver removal 



A basic rmmod ramoops segfaults. Let's see why.

Since commit 34f0ec82 ("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 ee1d2674 ("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 resources
were allocated. And then, in the free path, rely on ->max_dump_cnt in
the free path.

Cc: Anton Vorontsov <anton@enomsg.org>
Cc: Colin Cross <ccross@android.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Acked-by: default avatarNamhyung Kim <namhyung@kernel.org>
Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Cc: stable@vger.kernel.org # 4.4.x-
parent d71f0586

fs/pstore/ram.c

+12 −5
Original line number Diff line number Diff line
@@ -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;