[PATCH ethtool 4/6] ethtool: several fixes in do_gregs()

[Ivan Vecera]

- correctly close gregs_dump_file in case of fstat() failure
- check for error from realloc

Fixes: be4c2d0 ("ethtool.c: fix dump_regs heap corruption")
Cc: David Decotigny <de...@googlers.com>
Signed-off-by: Ivan Vecera <c...@cera.cz>
---
 ethtool.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/ethtool.c b/ethtool.c
index e7495fe..2b90984 100644
--- a/ethtool.c
+++ b/ethtool.c
@@ -3179,17 +3179,26 @@ static int do_gregs(struct cmd_context *ctx)
        if (!gregs_dump_raw && gregs_dump_file != NULL) {
                /* overwrite reg values from file dump */
                FILE *f = fopen(gregs_dump_file, "r");
+               struct ethtool_regs *nregs;
                struct stat st;
                size_t nread;
 
                if (!f || fstat(fileno(f), &st) < 0) {
                        fprintf(stderr, "Can't open '%s': %s\n",
                                gregs_dump_file, strerror(errno));
+                       if (f)
+                               fclose(f);
                        free(regs);
                        return 75;
                }
 
-               regs = realloc(regs, sizeof(*regs) + st.st_size);
+               nregs = realloc(regs, sizeof(*regs) + st.st_size);
+               if (!nregs) {
+                       perror("Cannot allocate memory for register dump");
+                       free(regs); /* was not freed by realloc */
+                       return 73;
+               }
+               regs = nregs;
                regs->len = st.st_size;
                nread = fread(regs->data, regs->len, 1, f);
                fclose(f);
-- 
2.16.4