[ethtool PATCH v4 04/11] ethtool.c: do_seeprom checks for params & stdin sanity

[David Decotigny]

From: David Decotigny <de...@googlers.com>

Tested:
  On qemu e1000:
  $ dd if=/dev/zero bs=2 count=5 | /mnt/ethtool -E eth0 length 9
  too much data from stdin
  $ dd if=/dev/zero bs=2 count=5 | /mnt/ethtool -E eth0 length 11
  not enough data from stdin
  $ dd if=/dev/zero bs=2 count=5 | /mnt/ethtool -E eth0 length 10
  Cannot set EEPROM data: Bad address


Signed-off-by: David Decotigny <de...@googlers.com>
---
 ethtool.c | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/ethtool.c b/ethtool.c
index 7c2b5cb..d349bee 100644
--- a/ethtool.c
+++ b/ethtool.c
@@ -2828,8 +2828,10 @@ static int do_seeprom(struct cmd_context *ctx)
        if (seeprom_length == -1)
                seeprom_length = drvinfo.eedump_len;
 
-       if (drvinfo.eedump_len < seeprom_offset + seeprom_length)
-               seeprom_length = drvinfo.eedump_len - seeprom_offset;
+       if (drvinfo.eedump_len < seeprom_offset + seeprom_length) {
+               fprintf(stderr, "offset & length out of bounds\n");
+               return 1;
+       }
 
        eeprom = calloc(1, sizeof(*eeprom)+seeprom_length);
        if (!eeprom) {
@@ -2844,8 +2846,18 @@ static int do_seeprom(struct cmd_context *ctx)
        eeprom->data[0] = seeprom_value;
 
        /* Multi-byte write: read input from stdin */
-       if (!seeprom_value_seen)
-               eeprom->len = fread(eeprom->data, 1, eeprom->len, stdin);
+       if (!seeprom_value_seen) {
+               if (1 != fread(eeprom->data, eeprom->len, 1, stdin)) {
+                       fprintf(stderr, "not enough data from stdin\n");
+                       free(eeprom);
+                       return 75;
+               }
+               if ((fgetc(stdin) != EOF) || !feof(stdin)) {
+                       fprintf(stderr, "too much data from stdin\n");
+                       free(eeprom);
+                       return 75;
+               }
+       }
 
        err = send_ioctl(ctx, eeprom);
        if (err < 0) {
-- 
2.7.0.rc3.207.g0ac5344