virt-host-validate: Allow longer list of CPU flags

On various occasions, virt-host-validate parses /proc/cpuinfo to
learn about CPU flags (see virHostValidateGetCPUFlags()). It does
so, by reading the file line by line until the line with CPU
flags is reached. Then the line is split into individual flags
(using space as a delimiter) and the list of flags is then
iterated over.

This works, except for cases when the line with CPU flags is too
long. Problem is - the line is capped at 1024 bytes and on newer
CPUs (and newer kernels), the line can be significantly longer.
I've seen a line that's ~1200 characters long (with 164 flags
reported).

Switch to unbounded read from the file (getline()).

Resolves: https://issues.redhat.com/browse/RHEL-39969
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Jiri Denemark <jdenemar@redhat.com>

diff --git a/tools/virt-host-validate-common.c b/tools/virt-host-validate-common.c
index 591143c24d15bd30d175bc3def3178af12ddc472..63cc3dbe7b3bef96927b3d088fdabe82a31cac98 100644 (file)
--- a/tools/virt-host-validate-common.c
+++ b/tools/virt-host-validate-common.c
@@ -106,21 +106,19 @@ virBitmap *virHostValidateGetCPUFlags(void)
 {
     FILE *fp;
     virBitmap *flags = NULL;
+    g_autofree char *line = NULL;
+    size_t linelen = 0;
 
     if (!(fp = fopen("/proc/cpuinfo", "r")))
         return NULL;
 
     flags = virBitmapNew(VIR_HOST_VALIDATE_CPU_FLAG_LAST);
 
-    do {
-        char line[1024];
+    while (getline(&line, &linelen, fp) > 0) {
         char *start;
         g_auto(GStrv) tokens = NULL;
         GStrv next;
 
-        if (!fgets(line, sizeof(line), fp))
-            break;
-
         /* The line we're interested in is marked differently depending
          * on the architecture, so check possible prefixes */
         if (!STRPREFIX(line, "flags") &&
@@ -129,11 +127,9 @@ virBitmap *virHostValidateGetCPUFlags(void)
             !STRPREFIX(line, "facilities"))
             continue;
 
-        /* fgets() includes the trailing newline in the output buffer,
-         * so we need to clean that up ourselves. We can safely access
-         * line[strlen(line) - 1] because the checks above would cause
-         * us to skip empty strings */
-        line[strlen(line) - 1] = '\0';
+        /* getline() may include the trailing newline in the output
+         * buffer, so we need to clean that up ourselves. */
+        virStringTrimOptionalNewline(line);
 
         /* Skip to the separator */
         if (!(start = strchr(line, ':')))
@@ -153,7 +149,7 @@ virBitmap *virHostValidateGetCPUFlags(void)
             if ((value = virHostValidateCPUFlagTypeFromString(*next)) >= 0)
                 ignore_value(virBitmapSetBit(flags, value));
         }
-    } while (1);
+    }
 
     VIR_FORCE_FCLOSE(fp);