Merge tag 'please-pull-pstore' of git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux

Pull pstore fixes from Tony Luck:
 "Series of small bug fixes for pstore"

* tag 'please-pull-pstore' of git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux:
  pstore: Fix memory leak when decompress using big_oops_buf
  pstore: Fix buffer overflow while write offset equal to buffer size
  pstore: Correct the max_dump_cnt clearing of ramoops
  pstore: Fix NULL pointer fault if get NULL prz in ramoops_get_next_prz
  pstore: skip zero size persistent ram buffer in traverse
  pstore: clarify clearing of _read_cnt in ramoops_context

fs/pstore/platform.c

@@ -497,6 +497,7 @@ void pstore_get_records(int quiet)
 							big_oops_buf_sz);
 
 			if (unzipped_len > 0) {
+				kfree(buf);
 				buf = big_oops_buf;
 				size = unzipped_len;
 				compressed = false;

fs/pstore/ram.c

@@ -86,6 +86,7 @@ struct ramoops_context {
 	struct persistent_ram_ecc_info ecc_info;
 	unsigned int max_dump_cnt;
 	unsigned int dump_write_cnt;
+	/* _read_cnt need clear on ramoops_pstore_open */
 	unsigned int dump_read_cnt;
 	unsigned int console_read_cnt;
 	unsigned int ftrace_read_cnt;
@@ -101,6 +102,7 @@ static int ramoops_pstore_open(struct pstore_info *psi)
 
 	cxt->dump_read_cnt = 0;
 	cxt->console_read_cnt = 0;
+	cxt->ftrace_read_cnt = 0;
 	return 0;
 }
 
@@ -117,13 +119,15 @@ ramoops_get_next_prz(struct persistent_ram_zone *przs[], uint *c, uint max,
 		return NULL;
 
 	prz = przs[i];
+	if (!prz)
+		return NULL;
 
-	if (update) {
 	/* Update old/shadowed buffer. */
+	if (update)
 		persistent_ram_save_old(prz);
+
 	if (!persistent_ram_old_size(prz))
 		return NULL;
-	}
 
 	*typep = type;
 	*id = i;
@@ -316,6 +320,7 @@ static void ramoops_free_przs(struct ramoops_context *cxt)
 {
 	int i;
 
+	cxt->max_dump_cnt = 0;
 	if (!cxt->przs)
 		return;
 
@@ -346,7 +351,7 @@ 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");
-		return -ENOMEM;
+		goto fail_prz;
 	}
 
 	for (i = 0; i < cxt->max_dump_cnt; i++) {
@@ -428,7 +433,6 @@ static int ramoops_probe(struct platform_device *pdev)
 	if (pdata->ftrace_size && !is_power_of_2(pdata->ftrace_size))
 		pdata->ftrace_size = rounddown_pow_of_two(pdata->ftrace_size);
 
-	cxt->dump_read_cnt = 0;
 	cxt->size = pdata->mem_size;
 	cxt->phys_addr = pdata->mem_address;
 	cxt->record_size = pdata->record_size;
@@ -505,7 +509,6 @@ static int ramoops_probe(struct platform_device *pdev)
 	kfree(cxt->pstore.buf);
 fail_clear:
 	cxt->pstore.bufsize = 0;
-	cxt->max_dump_cnt = 0;
 fail_cnt:
 	kfree(cxt->fprz);
 fail_init_fprz:

fs/pstore/ram_core.c

@@ -54,7 +54,7 @@ static size_t buffer_start_add_atomic(struct persistent_ram_zone *prz, size_t a)
 	do {
 		old = atomic_read(&prz->buffer->start);
 		new = old + a;
-		while (unlikely(new > prz->buffer_size))
+		while (unlikely(new >= prz->buffer_size))
 			new -= prz->buffer_size;
 	} while (atomic_cmpxchg(&prz->buffer->start, old, new) != old);
 
@@ -91,7 +91,7 @@ static size_t buffer_start_add_locked(struct persistent_ram_zone *prz, size_t a)
 
 	old = atomic_read(&prz->buffer->start);
 	new = old + a;
-	while (unlikely(new > prz->buffer_size))
+	while (unlikely(new >= prz->buffer_size))
 		new -= prz->buffer_size;
 	atomic_set(&prz->buffer->start, new);