mm, slab: cleanup slab_bug() parameters

[ Upstream commit 4b183dd9359d5772446cb634b12a383bed98c4fc ]

slab_err() has variadic printf arguments but instead of passing them to
slab_bug() it does vsnprintf() to a buffer and passes %s, buf.

To allow passing them directly, turn slab_bug() to __slab_bug() with a
va_list parameter, and slab_bug() a wrapper with fmt, ... parameters.
Then slab_err() can call __slab_bug() without the intermediate buffer.

Also constify fmt everywhere, which also simplifies object_err()'s
call to slab_bug().

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Harry Yoo <harry.yoo@oracle.com>
Stable-dep-of: b4efccec8d06 ("mm/slub: avoid accessing metadata when pointer is invalid in object_err()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/mm/slub.c b/mm/slub.c
index 40a6a5e7735b0d36db551be9af86bd9a1802a1be..7e1af40a65f06b9def4dbc942696bfdccbdfd54b 100644 (file)
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1027,12 +1027,12 @@ void skip_orig_size_check(struct kmem_cache *s, const void *object)
        set_orig_size(s, (void *)object, s->object_size);
 }
 
-static void slab_bug(struct kmem_cache *s, char *fmt, ...)
+static void __slab_bug(struct kmem_cache *s, const char *fmt, va_list argsp)
 {
        struct va_format vaf;
        va_list args;
 
-       va_start(args, fmt);
+       va_copy(args, argsp);
        vaf.fmt = fmt;
        vaf.va = &args;
        pr_err("=============================================================================\n");
@@ -1041,8 +1041,17 @@ static void slab_bug(struct kmem_cache *s, char *fmt, ...)
        va_end(args);
 }
 
+static void slab_bug(struct kmem_cache *s, const char *fmt, ...)
+{
+       va_list args;
+
+       va_start(args, fmt);
+       __slab_bug(s, fmt, args);
+       va_end(args);
+}
+
 __printf(2, 3)
-static void slab_fix(struct kmem_cache *s, char *fmt, ...)
+static void slab_fix(struct kmem_cache *s, const char *fmt, ...)
 {
        struct va_format vaf;
        va_list args;
@@ -1098,12 +1107,12 @@ static void print_trailer(struct kmem_cache *s, struct slab *slab, u8 *p)
 }
 
 static void object_err(struct kmem_cache *s, struct slab *slab,
-                       u8 *object, char *reason)
+                       u8 *object, const char *reason)
 {
        if (slab_add_kunit_errors())
                return;
 
-       slab_bug(s, "%s", reason);
+       slab_bug(s, reason);
        print_trailer(s, slab, object);
        add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
 
@@ -1139,15 +1148,14 @@ static __printf(3, 4) void slab_err(struct kmem_cache *s, struct slab *slab,
                        const char *fmt, ...)
 {
        va_list args;
-       char buf[100];
 
        if (slab_add_kunit_errors())
                return;
 
        va_start(args, fmt);
-       vsnprintf(buf, sizeof(buf), fmt, args);
+       __slab_bug(s, fmt, args);
        va_end(args);
-       slab_bug(s, "%s", buf);
+
        __slab_err(slab);
 }
 
@@ -1185,7 +1193,7 @@ static void init_object(struct kmem_cache *s, void *object, u8 val)
                                          s->inuse - poison_size);
 }
 
-static void restore_bytes(struct kmem_cache *s, char *message, u8 data,
+static void restore_bytes(struct kmem_cache *s, const char *message, u8 data,
                                                void *from, void *to)
 {
        slab_fix(s, "Restoring %s 0x%p-0x%p=0x%x", message, from, to - 1, data);
@@ -1200,7 +1208,7 @@ static void restore_bytes(struct kmem_cache *s, char *message, u8 data,
 
 static pad_check_attributes int
 check_bytes_and_report(struct kmem_cache *s, struct slab *slab,
-                      u8 *object, char *what, u8 *start, unsigned int value,
+                      u8 *object, const char *what, u8 *start, unsigned int value,
                       unsigned int bytes, bool slab_obj_print)
 {
        u8 *fault;