Merge tag 'pstore-v5.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull pstore cleanups from Kees Cook:

 - Remove some needless memory allocations (Yue Hu, Kees Cook)

 - Add zero-length checks to avoid no-op calls (Yue Hu)

* tag 'pstore-v5.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  pstore/ram: Avoid needless alloc during header write
  pstore/ram: Add kmsg hlen zero check to ramoops_pstore_write()
  pstore/ram: Move initialization earlier
  pstore: Avoid writing records with zero size
  pstore/ram: Replace dummy_data heap memory with stack memory

2 files changed, 32 insertions, 35 deletions

diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index 2d1066ed3c28..75887a269b64 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -501,6 +501,9 @@ static void pstore_console_write(struct console *con, const char *s, unsigned c)
 {
         struct pstore_record record;
 
+        if (!c)
+                return;
+
         pstore_record_init(&record, psinfo);
         record.type = PSTORE_TYPE_CONSOLE;
 
diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
index 898c8321b343..c5c685589e36 100644
--- a/fs/pstore/ram.c
+++ b/fs/pstore/ram.c
@@ -110,7 +110,6 @@ struct ramoops_context {
 };
 
 static struct platform_device *dummy;
-static struct ramoops_platform_data *dummy_data;
 
 static int ramoops_pstore_open(struct pstore_info *psi)
 {
@@ -346,17 +345,15 @@ out:
 static size_t ramoops_write_kmsg_hdr(struct persistent_ram_zone *prz,
                                      struct pstore_record *record)
 {
-        char *hdr;
+        char hdr[36]; /* "===="(4), %lld(20), "."(1), %06lu(6), "-%c\n"(3) */
         size_t len;
 
-        hdr = kasprintf(GFP_ATOMIC, RAMOOPS_KERNMSG_HDR "%lld.%06lu-%c\n",
+        len = scnprintf(hdr, sizeof(hdr),
+                RAMOOPS_KERNMSG_HDR "%lld.%06lu-%c\n",
                 (time64_t)record->time.tv_sec,
                 record->time.tv_nsec / 1000,
                 record->compressed ? 'C' : 'D');
-        WARN_ON_ONCE(!hdr);
-        len = hdr ? strlen(hdr) : 0;
         persistent_ram_write(prz, hdr, len);
-        kfree(hdr);
 
         return len;
 }
@@ -424,6 +421,9 @@ static int notrace ramoops_pstore_write(struct pstore_record *record)
 
         /* Build header and append record contents. */
         hlen = ramoops_write_kmsg_hdr(prz, record);
+        if (!hlen)
+                return -ENOMEM;
+
         size = record->size;
         if (size + hlen > prz->buffer_size)
                 size = prz->buffer_size - hlen;
@@ -716,15 +716,6 @@ static int ramoops_probe(struct platform_device *pdev)
         phys_addr_t paddr;
         int err = -EINVAL;
 
-        if (dev_of_node(dev) && !pdata) {
-                pdata = &pdata_local;
-                memset(pdata, 0, sizeof(*pdata));
-
-                err = ramoops_parse_dt(pdev, pdata);
-                if (err < 0)
-                        goto fail_out;
-        }
-
         /*
          * Only a single ramoops area allowed at a time, so fail extra
          * probes.
@@ -734,6 +725,15 @@ static int ramoops_probe(struct platform_device *pdev)
                 goto fail_out;
         }
 
+        if (dev_of_node(dev) && !pdata) {
+                pdata = &pdata_local;
+                memset(pdata, 0, sizeof(*pdata));
+
+                err = ramoops_parse_dt(pdev, pdata);
+                if (err < 0)
+                        goto fail_out;
+        }
+
         /* Make sure we didn't get bogus platform data pointer. */
         if (!pdata) {
                 pr_err("NULL platform data\n");
@@ -892,13 +892,12 @@ static inline void ramoops_unregister_dummy(void)
 {
         platform_device_unregister(dummy);
         dummy = NULL;
-
-        kfree(dummy_data);
-        dummy_data = NULL;
 }
 
 static void __init ramoops_register_dummy(void)
 {
+        struct ramoops_platform_data pdata;
+
         /*
          * Prepare a dummy platform data structure to carry the module
          * parameters. If mem_size isn't set, then there are no module
@@ -909,30 +908,25 @@ static void __init ramoops_register_dummy(void)
 
         pr_info("using module parameters\n");
 
-        dummy_data = kzalloc(sizeof(*dummy_data), GFP_KERNEL);
-        if (!dummy_data) {
-                pr_info("could not allocate pdata\n");
-                return;
-        }
-
-        dummy_data->mem_size = mem_size;
-        dummy_data->mem_address = mem_address;
-        dummy_data->mem_type = mem_type;
-        dummy_data->record_size = record_size;
-        dummy_data->console_size = ramoops_console_size;
-        dummy_data->ftrace_size = ramoops_ftrace_size;
-        dummy_data->pmsg_size = ramoops_pmsg_size;
-        dummy_data->dump_oops = dump_oops;
-        dummy_data->flags = RAMOOPS_FLAG_FTRACE_PER_CPU;
+        memset(&pdata, 0, sizeof(pdata));
+        pdata.mem_size = mem_size;
+        pdata.mem_address = mem_address;
+        pdata.mem_type = mem_type;
+        pdata.record_size = record_size;
+        pdata.console_size = ramoops_console_size;
+        pdata.ftrace_size = ramoops_ftrace_size;
+        pdata.pmsg_size = ramoops_pmsg_size;
+        pdata.dump_oops = dump_oops;
+        pdata.flags = RAMOOPS_FLAG_FTRACE_PER_CPU;
 
         /*
          * For backwards compatibility ramoops.ecc=1 means 16 bytes ECC
          * (using 1 byte for ECC isn't much of use anyway).
          */
-        dummy_data->ecc_info.ecc_size = ramoops_ecc == 1 ? 16 : ramoops_ecc;
+        pdata.ecc_info.ecc_size = ramoops_ecc == 1 ? 16 : ramoops_ecc;
 
         dummy = platform_device_register_data(NULL, "ramoops", -1,
-                        dummy_data, sizeof(struct ramoops_platform_data));
+                        &pdata, sizeof(pdata));
         if (IS_ERR(dummy)) {
                 pr_info("could not create platform device: %ld\n",
                         PTR_ERR(dummy));