From 836b2fe544a5e9b5ce116622cb36fba33838c6fd Mon Sep 17 00:00:00 2001 From: Eduard Zingerman Date: Fri, 4 Sep 2026 01:33:23 -0700 Subject: selftests/bpf: Check that JMP32 pointer vs zero jumps are not predicted Add jmp32_ptr_vs_zero_jne: the fall-through of the 32-bit compare, which the verifier used to skip, contains an out of bounds map value access, hence w/o the previous patch the program is accepted. See previous patch for detailed description. Reported-by: Nicholas Carlini Suggested-by: Nicholas Carlini Signed-off-by: Eduard Zingerman Link: https://lore.kernel.org/bpf/20260904083325.2083493-6-eddyz87@gmail.com Signed-off-by: Kumar Kartikeya Dwivedi --- lib/kasprintf.c | 64 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 64 insertions(+) create mode 100644 lib/kasprintf.c (limited to 'lib/kasprintf.c') diff --git a/lib/kasprintf.c b/lib/kasprintf.c new file mode 100644 index 000000000..cd2f5974e --- /dev/null +++ b/lib/kasprintf.c @@ -0,0 +1,64 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * linux/lib/kasprintf.c + * + * Copyright (C) 1991, 1992 Linus Torvalds + */ + +#include +#include +#include +#include +#include + +/* Simplified asprintf. */ +char *kvasprintf(gfp_t gfp, const char *fmt, va_list ap) +{ + unsigned int first, second; + char *p; + va_list aq; + + va_copy(aq, ap); + first = vsnprintf(NULL, 0, fmt, aq); + va_end(aq); + + p = kmalloc_track_caller(first+1, gfp); + if (!p) + return NULL; + + second = vsnprintf(p, first+1, fmt, ap); + WARN(first != second, "different return values (%u and %u) from vsnprintf(\"%s\", ...)", + first, second, fmt); + + return p; +} +EXPORT_SYMBOL(kvasprintf); + +/* + * If fmt contains no % (or is exactly %s), use kstrdup_const. If fmt + * (or the sole vararg) points to rodata, we will then save a memory + * allocation and string copy. In any case, the return value should be + * freed using kfree_const(). + */ +const char *kvasprintf_const(gfp_t gfp, const char *fmt, va_list ap) +{ + if (!strchr(fmt, '%')) + return kstrdup_const(fmt, gfp); + if (!strcmp(fmt, "%s")) + return kstrdup_const(va_arg(ap, const char*), gfp); + return kvasprintf(gfp, fmt, ap); +} +EXPORT_SYMBOL(kvasprintf_const); + +char *kasprintf(gfp_t gfp, const char *fmt, ...) +{ + va_list ap; + char *p; + + va_start(ap, fmt); + p = kvasprintf(gfp, fmt, ap); + va_end(ap); + + return p; +} +EXPORT_SYMBOL(kasprintf); -- cgit v1.3.1