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Wed, 10 Sep 2025 15:25:14 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id +5XFE1qYwWgvNgAAD6G6ig (envelope-from ); Wed, 10 Sep 2025 15:25:14 +0000 From: Fabian Vogt To: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Guo Ren , Marvin Friedrich , Alexandre Ghiti , Albert Ou , Palmer Dabbelt , Paul Walmsley , =?UTF-8?B?QmrDtnJuIFTDtnBlbA==?= Subject: [PATCH] riscv: kprobes: Fix probe address validation Date: Wed, 10 Sep 2025 17:25:13 +0200 Message-ID: <6191817.lOV4Wx5bFT@fvogt-thinkpad> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" X-Spam-Level: X-Spamd-Result: default: False [-3.30 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; CTE_CASE(0.50)[]; MID_RHS_NOT_FQDN(0.50)[]; NEURAL_HAM_SHORT(-0.20)[-0.999]; MIME_GOOD(-0.10)[text/plain]; MIME_TRACE(0.00)[0:+]; TO_MATCH_ENVRCPT_ALL(0.00)[]; ARC_NA(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FUZZY_RATELIMITED(0.00)[rspamd.com]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; FROM_EQ_ENVFROM(0.00)[]; RCVD_TLS_ALL(0.00)[]; RCPT_COUNT_SEVEN(0.00)[9]; MISSING_XM_UA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo,suse.com:email,suse.de:email] X-Spam-Flag: NO X-Spam-Score: -3.30 When adding a kprobe such as "p:probe/tcp_sendmsg _text+15392192", arch_check_kprobe would start iterating all instructions starting from _text until the probed address. Not only is this very inefficient, but literal values in there (e.g. left by function patching) are misinterpreted in a way that causes a desync. Fix this by doing it like x86: start the iteration at the closest preceding symbol instead of the given starting point. Fixes: 87f48c7ccc73 ("riscv: kprobe: Fixup kernel panic when probing an ill= egal position") Signed-off-by: Fabian Vogt Signed-off-by: Marvin Friedrich --- arch/riscv/kernel/probes/kprobes.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/arch/riscv/kernel/probes/kprobes.c b/arch/riscv/kernel/probes/= kprobes.c index c0738d6c6498..8723390c7cad 100644 --- a/arch/riscv/kernel/probes/kprobes.c +++ b/arch/riscv/kernel/probes/kprobes.c @@ -49,10 +49,15 @@ static void __kprobes arch_simulate_insn(struct kprobe = *p, struct pt_regs *regs) post_kprobe_handler(p, kcb, regs); } =20 -static bool __kprobes arch_check_kprobe(struct kprobe *p) +static bool __kprobes arch_check_kprobe(unsigned long addr) { - unsigned long tmp =3D (unsigned long)p->addr - p->offset; - unsigned long addr =3D (unsigned long)p->addr; + unsigned long tmp, offset; + + /* start iterating at the closest preceding symbol */ + if (!kallsyms_lookup_size_offset(addr, NULL, &offset)) + return false; + + tmp =3D addr - offset; =20 while (tmp <=3D addr) { if (tmp =3D=3D addr) @@ -71,7 +76,7 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p) if ((unsigned long)insn & 0x1) return -EILSEQ; =20 - if (!arch_check_kprobe(p)) + if (!arch_check_kprobe((unsigned long)p->addr)) return -EILSEQ; =20 /* copy instruction */ --=20 2.51.0