4.8-stable review patch. If anyone has any objections, please let me know.
------------------
From: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
commit 4407de74df18ed405cc5998990004c813ccfdbde upstream.
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 resources
were allocated. And then, in the free path, rely on ->max_dump_cnt in
the free path.
Cc: Anton Vorontsov <anton@xxxxxxxxxx>
Cc: Colin Cross <ccross@xxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Acked-by: Namhyung Kim <namhyung@xxxxxxxxxx>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/pstore/ram.c | 17 ++++++++++++-----
1 file changed, 12 insertions(+), 5 deletions(-)
--- a/fs/pstore/ram.c
+++ b/fs/pstore/ram.c
@@ -377,13 +377,14 @@ static void ramoops_free_przs(struct ram
{
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 devi
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 devi
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 devi
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 platfor
struct ramoops_context *cxt = &oops_cxt;
pstore_unregister(&cxt->pstore);
- cxt->max_dump_cnt = 0;
kfree(cxt->pstore.buf);
cxt->pstore.bufsize = 0;
--
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