[PATCH] reiserfs: check/extend buffer length for printing functions

[Chen Gang]

If format string and/or error string are larger than 1024, it will
cause memory overflow.

So need check the format string buffer length before process it.

Also need use (v)snprintf() instread of (v)sprintf() for error buffer
to be sure of maximize length limitation.

Normally, the error buffer length need be much larger than format
buffer length, so extend the error buffer length to 4096.

When adding new code, also need let them within 80 column.


Signed-off-by: Chen Gang <gang.chen@xxxxxxxxxxx>
---
 fs/reiserfs/prints.c |   90 ++++++++++++++++++++++++++++++-------------------
 1 files changed, 55 insertions(+), 35 deletions(-)

diff --git a/fs/reiserfs/prints.c b/fs/reiserfs/prints.c
index c0b1112..6b7581e 100644
--- a/fs/reiserfs/prints.c
+++ b/fs/reiserfs/prints.c
@@ -10,8 +10,13 @@
 
 #include <stdarg.h>
 
-static char error_buf[1024];
-static char fmt_buf[1024];
+#define REISERFS_MAX_FMT_BUF		1024
+#define REISERFS_MAX_ERROR_BUF		4096
+#define REISERFS_ERR_BUF_LEFT(pos, base)	\
+				(REISERFS_MAX_ERROR_BUF - ((pos) - (base)))
+
+static char error_buf[REISERFS_MAX_FMT_BUF];
+static char fmt_buf[REISERFS_MAX_ERROR_BUF];
 static char off_buf[80];
 
 static char *reiserfs_cpu_offset(struct cpu_key *key)
@@ -76,72 +81,74 @@ static char *le_type(struct reiserfs_key *key)
 }
 
 /* %k */
-static void sprintf_le_key(char *buf, struct reiserfs_key *key)
+static void sprintf_le_key(char *buf, int left, struct reiserfs_key *key)
 {
 	if (key)
-		sprintf(buf, "[%d %d %s %s]", le32_to_cpu(key->k_dir_id),
+		snprintf(buf, left, "[%d %d %s %s]", le32_to_cpu(key->k_dir_id),
 			le32_to_cpu(key->k_objectid), le_offset(key),
 			le_type(key));
 	else
-		sprintf(buf, "[NULL]");
+		snprintf(buf, left, "[NULL]");
 }
 
 /* %K */
-static void sprintf_cpu_key(char *buf, struct cpu_key *key)
+static void sprintf_cpu_key(char *buf, int left, struct cpu_key *key)
 {
 	if (key)
-		sprintf(buf, "[%d %d %s %s]", key->on_disk_key.k_dir_id,
+		snprintf(buf, left, "[%d %d %s %s]", key->on_disk_key.k_dir_id,
 			key->on_disk_key.k_objectid, reiserfs_cpu_offset(key),
 			cpu_type(key));
 	else
-		sprintf(buf, "[NULL]");
+		snprintf(buf, left, "[NULL]");
 }
 
-static void sprintf_de_head(char *buf, struct reiserfs_de_head *deh)
+static void sprintf_de_head(char *buf, int left, struct reiserfs_de_head *deh)
 {
 	if (deh)
-		sprintf(buf,
+		snprintf(buf, left,
 			"[offset=%d dir_id=%d objectid=%d location=%d state=%04x]",
 			deh_offset(deh), deh_dir_id(deh), deh_objectid(deh),
 			deh_location(deh), deh_state(deh));
 	else
-		sprintf(buf, "[NULL]");
+		snprintf(buf, left, "[NULL]");
 
 }
 
-static void sprintf_item_head(char *buf, struct item_head *ih)
+static void sprintf_item_head(char *buf, int left, struct item_head *ih)
 {
 	if (ih) {
-		strcpy(buf,
+		snprintf(buf, left, "%s",
 		       (ih_version(ih) == KEY_FORMAT_3_6) ? "*3.6* " : "*3.5*");
-		sprintf_le_key(buf + strlen(buf), &(ih->ih_key));
-		sprintf(buf + strlen(buf), ", item_len %d, item_location %d, "
-			"free_space(entry_count) %d",
+		sprintf_le_key(buf + strlen(buf), left - strlen(buf),
+			       &(ih->ih_key));
+		snprintf(buf + strlen(buf), left - strlen(buf),
+			 ", item_len %d, item_location %d, free_space(entry_count) %d",
 			ih_item_len(ih), ih_location(ih), ih_free_space(ih));
 	} else
-		sprintf(buf, "[NULL]");
+		snprintf(buf, left, "[NULL]");
 }
 
-static void sprintf_direntry(char *buf, struct reiserfs_dir_entry *de)
+static void sprintf_direntry(char *buf, int left, struct reiserfs_dir_entry *de)
 {
 	char name[20];
 
 	memcpy(name, de->de_name, de->de_namelen > 19 ? 19 : de->de_namelen);
 	name[de->de_namelen > 19 ? 19 : de->de_namelen] = 0;
-	sprintf(buf, "\"%s\"==>[%d %d]", name, de->de_dir_id, de->de_objectid);
+	snprintf(buf, left, "\"%s\"==>[%d %d]",
+		 name, de->de_dir_id, de->de_objectid);
 }
 
-static void sprintf_block_head(char *buf, struct buffer_head *bh)
+static void sprintf_block_head(char *buf, int left, struct buffer_head *bh)
 {
-	sprintf(buf, "level=%d, nr_items=%d, free_space=%d rdkey ",
+	snprintf(buf, left, "level=%d, nr_items=%d, free_space=%d rdkey ",
 		B_LEVEL(bh), B_NR_ITEMS(bh), B_FREE_SPACE(bh));
 }
 
-static void sprintf_buffer_head(char *buf, struct buffer_head *bh)
+static void sprintf_buffer_head(char *buf, int left, struct buffer_head *bh)
 {
 	char b[BDEVNAME_SIZE];
 
-	sprintf(buf,
+	snprintf(buf, left,
 		"dev %s, size %zd, blocknr %llu, count %d, state 0x%lx, page %p, (%s, %s, %s)",
 		bdevname(bh->b_bdev, b), bh->b_size,
 		(unsigned long long)bh->b_blocknr, atomic_read(&(bh->b_count)),
@@ -151,9 +158,9 @@ static void sprintf_buffer_head(char *buf, struct buffer_head *bh)
 		buffer_locked(bh) ? "LOCKED" : "UNLOCKED");
 }
 
-static void sprintf_disk_child(char *buf, struct disk_child *dc)
+static void sprintf_disk_child(char *buf, int left, struct disk_child *dc)
 {
-	sprintf(buf, "[dc_number=%d, dc_size=%u]", dc_block_number(dc),
+	snprintf(buf, left, "[dc_number=%d, dc_size=%u]", dc_block_number(dc),
 		dc_size(dc));
 }
 
@@ -190,8 +197,16 @@ static void prepare_error_buf(const char *fmt, va_list args)
 	char *fmt1 = fmt_buf;
 	char *k;
 	char *p = error_buf;
+	int left = REISERFS_ERR_BUF_LEFT(p, error_buf);
 	int what;
 
+	if (strlen(fmt) >= REISERFS_MAX_FMT_BUF) {
+		printk(KERN_CRIT
+			"REISERFS error (format buffer too long, more than %d): %s\n",
+			REISERFS_MAX_FMT_BUF, fmt);
+		return;
+	}
+
 	spin_lock(&error_lock);
 
 	strcpy(fmt1, fmt);
@@ -199,46 +214,51 @@ static void prepare_error_buf(const char *fmt, va_list args)
 	while ((k = is_there_reiserfs_struct(fmt1, &what)) != NULL) {
 		*k = 0;
 
-		p += vsprintf(p, fmt1, args);
+		p += vsnprintf(p, left, fmt1, args);
+		left = REISERFS_ERR_BUF_LEFT(p, error_buf);
 
 		switch (what) {
 		case 'k':
-			sprintf_le_key(p, va_arg(args, struct reiserfs_key *));
+			sprintf_le_key(p, left,
+				       va_arg(args, struct reiserfs_key *));
 			break;
 		case 'K':
-			sprintf_cpu_key(p, va_arg(args, struct cpu_key *));
+			sprintf_cpu_key(p, left,
+					va_arg(args, struct cpu_key *));
 			break;
 		case 'h':
-			sprintf_item_head(p, va_arg(args, struct item_head *));
+			sprintf_item_head(p, left,
+					  va_arg(args, struct item_head *));
 			break;
 		case 't':
-			sprintf_direntry(p,
+			sprintf_direntry(p, left,
 					 va_arg(args,
 						struct reiserfs_dir_entry *));
 			break;
 		case 'y':
-			sprintf_disk_child(p,
+			sprintf_disk_child(p, left,
 					   va_arg(args, struct disk_child *));
 			break;
 		case 'z':
-			sprintf_block_head(p,
+			sprintf_block_head(p, left,
 					   va_arg(args, struct buffer_head *));
 			break;
 		case 'b':
-			sprintf_buffer_head(p,
+			sprintf_buffer_head(p, left,
 					    va_arg(args, struct buffer_head *));
 			break;
 		case 'a':
-			sprintf_de_head(p,
+			sprintf_de_head(p, left,
 					va_arg(args,
 					       struct reiserfs_de_head *));
 			break;
 		}
 
 		p += strlen(p);
+		left = REISERFS_ERR_BUF_LEFT(p, error_buf);
 		fmt1 = k + 2;
 	}
-	vsprintf(p, fmt1, args);
+	vsnprintf(p, left, fmt1, args);
 	spin_unlock(&error_lock);
 
 }
-- 
1.7.7.6
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