[PATCH 2/4] libmpathpersist: format_transportids(): avoid PROUT overflow

[mwilck@xxxxxxxx]

From: Martin Wilck <mwilck@xxxxxxxx>

This limits the PERSISTENT RESERVE OUT data size to max. 8192 bytes.

Signed-off-by: Martin Wilck <mwilck@xxxxxxxx>
---
 libmpathpersist/mpath_pr_ioctl.c | 26 ++++++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/libmpathpersist/mpath_pr_ioctl.c b/libmpathpersist/mpath_pr_ioctl.c
index 1a28cba7..8bf16c0d 100644
--- a/libmpathpersist/mpath_pr_ioctl.c
+++ b/libmpathpersist/mpath_pr_ioctl.c
@@ -1,5 +1,6 @@
 #include <stdio.h>
 #include <stdlib.h>
+#include <stddef.h>
 
 #include <sys/types.h>
 #include <sys/stat.h>
@@ -138,38 +139,59 @@ retry :
 	return status;
 }
 
+#define check_overflow(ofs, n, start, label)				\
+	do {								\
+		if ((ofs) + 4 + (n) +					\
+		    offsetof(struct prout_param_descriptor, private_buffer) \
+		    > MPATH_MAX_PARAM_LEN)				\
+		{							\
+			(ofs) = (start);				\
+			goto label;					\
+		}							\
+	} while(0)
+
 uint32_t  format_transportids(struct prout_param_descriptor *paramp)
 {
 	unsigned int i = 0, len;
 	uint32_t buff_offset = 4;
-	memset(paramp->private_buffer, 0, MPATH_MAX_PARAM_LEN);
+	memset(paramp->private_buffer, 0, sizeof(paramp->private_buffer));
 	for (i=0; i < paramp->num_transportid; i++ )
 	{
+		uint32_t start_offset = buff_offset;
+
+		check_overflow(buff_offset, 1, start_offset, end_loop);
 		paramp->private_buffer[buff_offset] = (uint8_t)((paramp->trnptid_list[i]->format_code & 0xff)|
 							(paramp->trnptid_list[i]->protocol_id & 0xff));
 		buff_offset += 1;
 		switch(paramp->trnptid_list[i]->protocol_id)
 		{
 			case MPATH_PROTOCOL_ID_FC:
+				check_overflow(buff_offset, 7 + 8 + 8,
+					       start_offset, end_loop);
 				buff_offset += 7;
 				memcpy(&paramp->private_buffer[buff_offset], &paramp->trnptid_list[i]->n_port_name, 8);
 				buff_offset +=8 ;
 				buff_offset +=8 ;
 				break;
 			case MPATH_PROTOCOL_ID_SAS:
+				check_overflow(buff_offset, 3 + 12,
+					       start_offset, end_loop);
 				buff_offset += 3;
 				memcpy(&paramp->private_buffer[buff_offset], &paramp->trnptid_list[i]->sas_address, 8);
 				buff_offset += 12;
 				break;
 			case MPATH_PROTOCOL_ID_ISCSI:
-				buff_offset += 1;
 				len = (paramp->trnptid_list[i]->iscsi_name[1] & 0xff)+2;
+				check_overflow(buff_offset, 1 + len,
+					       start_offset, end_loop);
+				buff_offset += 1;
 				memcpy(&paramp->private_buffer[buff_offset], &paramp->trnptid_list[i]->iscsi_name,len);
 				buff_offset += len ;
 				break;
 		}
 
 	}
+end_loop:
 	buff_offset -= 4;
 	paramp->private_buffer[0] = (unsigned char)((buff_offset >> 24) & 0xff);
 	paramp->private_buffer[1] = (unsigned char)((buff_offset >> 16) & 0xff);
-- 
2.25.1


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