From 33a154a96e71a34a1bcca9f40da343dbbf7b38b4 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Thu, 1 Oct 2026 14:52:55 +0000 Subject: selftests/bpf: Test packet range of pointers sharing an id Add tests where two packet pointers share an id and tightening one pointer's umax from its var_off would put it less than their constant distance from the other's umax: with an index & 0x38 capped at 50, the base pointer keeps umax 50, so the pointer 8 bytes further on must keep umax 58, even though its known bits allow at most 56. These refused a valid program or accepted an out-of-bounds access before the fix: - check the advanced copy, load through the base: valid, was refused; - check the base, load the byte at base + 1 through a copy advanced by 8: was accepted; - check base + 4, load 4 bytes at base + 2 through base + 8: reads two bytes past the checked range, was accepted; - the same as the second with data_meta pointers checked against data: was accepted. These pass with and without the fix and cover nearby paths: - subtract an unknown scalar from a checked pointer and load below it (the range is kept across a new id); - reach a load through two paths whose checks cover 8 and 7 bytes after the loaded pointer; the second path must not be pruned by the first; - spill a copy of a pointer, check the pointer, fill the copy and load one byte past the checked range: the load is refused, and the copy has the range of the check. Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20261001145255.855630-2-alexei.starovoitov@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