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pstore/ramoops: fixup driver removal

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

Since commit 34f0ec82e0 ("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 ee1d267423 ("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: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: stable@vger.kernel.org # 4.4.x-
This commit is contained in:
Sebastian Andrzej Siewior 2016-09-08 13:48:05 +02:00 committed by Kees Cook
parent d71f058617
commit 4407de74df
1 changed files with 12 additions and 5 deletions
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17
fs/pstore/ram.c
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@ -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;