[PATCH 1/2] Consistently use read_file() when reading from a dump file

[Jean Delvare]

Use read_file() instead of mem_chunk() to read the entry point from a
dump file. This is faster, and consistent with how we then read the
actual DMI table from that dump file.

This made no functional difference so far, which is why it went
unnoticed for years. But now that a file type check was added to the
mem_chunk() function, we must stop using it to read from regular
files.

In practice, this will again allow root to use the --from-dump
option. I'm not too concerned about this temporary breakage though, as
there is no legitimate use case. Option --from-dump is precisely
meant to separate table fetching (which does require root and local
access) from decoding (which doesn't), so root should never use it.

Signed-off-by: Jean Delvare <jdelvare@suse.de>
---
 dmidecode.c |   11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

--- dmidecode.orig/dmidecode.c
+++ dmidecode/dmidecode.c
@@ -6025,17 +6025,25 @@ int main(int argc, char * const argv[])
                pr_comment("dmidecode %s", VERSION);
 
        /* Read from dump if so instructed */
+       size = 0x20;
        if (opt.flags & FLAG_FROM_DUMP)
        {
                if (!(opt.flags & FLAG_QUIET))
                        pr_info("Reading SMBIOS/DMI data from file %s.",
                                opt.dumpfile);
-               if ((buf = mem_chunk(0, 0x20, opt.dumpfile)) == NULL)
+               if ((buf = read_file(0, &size, opt.dumpfile)) == NULL)
                {
                        ret = 1;
                        goto exit_free;
                }
 
+               /* Truncated entry point can't be processed */
+               if (size < 0x20)
+               {
+                       ret = 1;
+                       goto done;
+               }
+
                if (memcmp(buf, "_SM3_", 5) == 0)
                {
                        if (smbios3_decode(buf, opt.dumpfile, 0))
@@ -6059,7 +6067,6 @@ int main(int argc, char * const argv[])
         * contain one of several types of entry points, so read enough for
         * the largest one, then determine what type it contains.
         */
-       size = 0x20;
        if (!(opt.flags & FLAG_NO_SYSFS)
         && (buf = read_file(0, &size, SYS_ENTRY_FILE)) != NULL)
        {


-- 
Jean Delvare
SUSE L3 Support