[xen master] xen/common: llc-coloring: clear color count on parse failure

[patchbot@xxxxxxx]

commit 16558646c8464ee32891096bf2d962b7e7213769
Author:     Mykola Kvach <mykola_kvach@xxxxxxxx>
AuthorDate: Thu May 21 21:41:21 2026 +0300
Commit:     Michal Orzel <michal.orzel@xxxxxxx>
CommitDate: Mon May 25 12:49:54 2026 +0200

    xen/common: llc-coloring: clear color count on parse failure
    
    parse_color_config() updates the caller-provided color count while
    parsing. If parsing later fails, leave the count at zero so callers
    do not consume a partially parsed configuration.
    
    The bug is reachable in practice: cmdline_parse() ignores the -EINVAL
    from a custom_param callback, so boot continues with the partial
    xen_num_colors / dom0_num_colors that llc_coloring_init() and
    dom0_set_llc_colors() then consume.
    
    Fixes: 6cdea3444eaf ("xen/arm: add Dom0 cache coloring support")
    Signed-off-by: Mykola Kvach <mykola_kvach@xxxxxxxx>
    Reviewed-by: Michal Orzel <michal.orzel@xxxxxxx>
    Reviewed-by: Denis Mukhin <dmukhin@xxxxxxxx>
    Release-Acked-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
---
 xen/common/llc-coloring.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/xen/common/llc-coloring.c b/xen/common/llc-coloring.c
index 6dc614739a..2606cb0977 100644
--- a/xen/common/llc-coloring.c
+++ b/xen/common/llc-coloring.c
@@ -79,7 +79,7 @@ static int __init parse_color_config(const char *buf, 
unsigned int colors[],
         if ( end >= NR_LLC_COLORS || start > end ||
              (end - start) >= (UINT_MAX - *num_colors) ||
              (*num_colors + (end - start)) >= max_num_colors )
-            return -EINVAL;
+            goto fail;
 
         /* Colors are range checked in check_colors() */
         for ( color = start; color <= end; color++ )
@@ -91,7 +91,14 @@ static int __init parse_color_config(const char *buf, 
unsigned int colors[],
             break;
     }
 
-    return *s ? -EINVAL : 0;
+    if ( *s )
+        goto fail;
+
+    return 0;
+
+ fail:
+    *num_colors = 0;
+    return -EINVAL;
 }
 
 static int __init parse_dom0_colors(const char *s)
--
generated by git-patchbot for /home/xen/git/xen.git#master