Blackfin arch: Fix bug - do not overflow the buffer given to us which tends to happen when CONFIG_L1_MAX_PIECE is increased past its default

Singed-off-by: Mike Frysinger <vapier.adi@gmail.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>

1 files changed, 26 insertions, 12 deletions

diff --git a/arch/blackfin/mm/blackfin_sram.c b/arch/blackfin/mm/blackfin_sram.c
index 3246f91c7baa..8f6fdc245330 100644
--- a/arch/blackfin/mm/blackfin_sram.c
+++ b/arch/blackfin/mm/blackfin_sram.c
@@ -549,13 +549,16 @@ EXPORT_SYMBOL(sram_alloc_with_lsl);
 /* Once we get a real allocator, we'll throw all of this away.
  * Until then, we need some sort of visibility into the L1 alloc.
  */
-static void _l1sram_proc_read(char *buf, int *len, const char *desc,
+/* Need to keep line of output the same.  Currently, that is 44 bytes
+ * (including newline).
+ */
+static int _l1sram_proc_read(char *buf, int *len, int count, const char *desc,
                 struct l1_sram_piece *pfree, const int array_size)
 {
         int i;
 
-        *len += sprintf(&buf[*len], "--- L1 %-14s Size  PID State\n", desc);
-        for (i = 0; i < array_size; ++i) {
+        *len += sprintf(&buf[*len], "--- L1 %-14s Size   PID State     \n", desc);
+        for (i = 0; i < array_size && *len < count; ++i) {
                 const char *alloc_type;
                 switch (pfree[i].flag) {
                 case SRAM_SLT_NULL:      alloc_type = "NULL"; break;
@@ -563,31 +566,42 @@ static void _l1sram_proc_read(char *buf, int *len, const char *desc,
                 case SRAM_SLT_ALLOCATED: alloc_type = "ALLOCATED"; break;
                 default:                 alloc_type = "????"; break;
                 }
-                *len += sprintf(&buf[*len], "%p-%p %8i %4i %s\n",
+                /* if we've got a lot of space to cover, omit things */
+                if ((PAGE_SIZE - 1024) < (CONFIG_L1_MAX_PIECE + 1) * 4 * 44 &&
+                    pfree[i].size == 0)
+                        continue;
+                *len += sprintf(&buf[*len], "%p-%p %8i %5i %-10s\n",
                         pfree[i].paddr, pfree[i].paddr + pfree[i].size,
                         pfree[i].size, pfree[i].pid, alloc_type);
         }
+        return (i != array_size);
 }
 static int l1sram_proc_read(char *buf, char **start, off_t offset, int count,
                 int *eof, void *data)
 {
         int len = 0;
 
-        _l1sram_proc_read(buf, &len, "Scratchpad",
-                        l1_ssram, ARRAY_SIZE(l1_ssram));
+        if (_l1sram_proc_read(buf, &len, count, "Scratchpad",
+                        l1_ssram, ARRAY_SIZE(l1_ssram)))
+                goto not_done;
 #if L1_DATA_A_LENGTH != 0
-        _l1sram_proc_read(buf, &len, "Data A",
-                        l1_data_A_sram, ARRAY_SIZE(l1_data_A_sram));
+        if (_l1sram_proc_read(buf, &len, count, "Data A",
+                        l1_data_A_sram, ARRAY_SIZE(l1_data_A_sram)))
+                goto not_done;
 #endif
 #if L1_DATA_B_LENGTH != 0
-        _l1sram_proc_read(buf, &len, "Data B",
-                        l1_data_B_sram, ARRAY_SIZE(l1_data_B_sram));
+        if (_l1sram_proc_read(buf, &len, count, "Data B",
+                        l1_data_B_sram, ARRAY_SIZE(l1_data_B_sram)))
+                goto not_done;
 #endif
 #if L1_CODE_LENGTH != 0
-        _l1sram_proc_read(buf, &len, "Instruction",
-                        l1_inst_sram, ARRAY_SIZE(l1_inst_sram));
+        if (_l1sram_proc_read(buf, &len, count, "Instruction",
+                        l1_inst_sram, ARRAY_SIZE(l1_inst_sram)))
+                goto not_done;
 #endif
 
+        *eof = 1;
+ not_done:
         return len;
 }