x86, UV: Use allocated buffer in tlb_uv.c:tunables_read()

The original code didn't check that the value returned from
snprintf() was less than the size of the buffer.  Although it
didn't cause a runtime bug in this case, it makes the static
checkers complain.

Andrew Morton suggested a dynamically sized buffer would be
cleaner.

Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dan Carpenter <error27@gmail.com>
Cc: Cliff Wickman <cpw@sgi.com>
Cc: Jack Steiner <steiner@sgi.com>
Cc: Robin Holt <holt@sgi.com>
LKML-Reference: <20100929083118.GA6376@bicker>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/arch/x86/kernel/tlb_uv.c b/arch/x86/kernel/tlb_uv.c
index 312ef0292815f1a3a757c10d3f994d67702b3531..33e77e4f7c866b0ff3113fcfffa08c9bbef788ed 100644 (file)
--- a/arch/x86/kernel/tlb_uv.c
+++ b/arch/x86/kernel/tlb_uv.c
@@ -1001,10 +1001,10 @@ static int uv_ptc_seq_show(struct seq_file *file, void *data)
 static ssize_t tunables_read(struct file *file, char __user *userbuf,
                                                size_t count, loff_t *ppos)
 {
-       char buf[300];
+       char *buf;
        int ret;
 
-       ret = snprintf(buf, 300, "%s %s %s\n%d %d %d %d %d %d %d %d %d\n",
+       buf = kasprintf(GFP_KERNEL, "%s %s %s\n%d %d %d %d %d %d %d %d %d\n",
                "max_bau_concurrent plugged_delay plugsb4reset",
                "timeoutsb4reset ipi_reset_limit complete_threshold",
                "congested_response_us congested_reps congested_period",
@@ -1012,7 +1012,12 @@ static ssize_t tunables_read(struct file *file, char __user *userbuf,
                timeoutsb4reset, ipi_reset_limit, complete_threshold,
                congested_response_us, congested_reps, congested_period);
 
-       return simple_read_from_buffer(userbuf, count, ppos, buf, ret);
+       if (!buf)
+               return -ENOMEM;
+
+       ret = simple_read_from_buffer(userbuf, count, ppos, buf, strlen(buf));
+       kfree(buf);
+       return ret;
 }
 
 /*