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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-490b29f49b8sm25092905e9.15.2026.06.02.02.25.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 02 Jun 2026 02:25:40 -0700 (PDT) Date: Tue, 2 Jun 2026 10:25:39 +0100 From: David Laight To: Aiden Bowling Cc: Lorenzo Stoakes , Andrew Morton , David Hildenbrand , Vlastimil Babka , linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH] kernel/sys.c: fix prctl_set_auxv to use sizeof instead of user-supplied len Message-ID: <20260602102539.07f8d1fe@pumpkin> In-Reply-To: <20260602024001.14119-2-aidenlbowling56@gmail.com> References: <20260602024001.14119-2-aidenlbowling56@gmail.com> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Mon, 1 Jun 2026 22:40:02 -0400 Aiden Bowling wrote: > prctl_set_auxv() passed the user-supplied 'len' to memcpy() when copying > into mm->saved_auxv, instead of sizeof(user_auxv). Since user_auxv is > already sized to the full auxv buffer, using 'len' risks a partial write > if the caller supplies a smaller value. Use sizeof(user_auxv) to always > copy the full buffer after validation. Is it possibly that the caller only wants to write the first few values? -- David > > Signed-off-by: Aiden Bowling > --- > kernel/sys.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/sys.c b/kernel/sys.c > index 62e842055cc9..d3f5229649e3 100644 > --- a/kernel/sys.c > +++ b/kernel/sys.c > @@ -2189,7 +2189,7 @@ static int prctl_set_auxv(struct mm_struct *mm, unsigned long addr, > BUILD_BUG_ON(sizeof(user_auxv) != sizeof(mm->saved_auxv)); > > task_lock(current); > - memcpy(mm->saved_auxv, user_auxv, len); > + memcpy(mm->saved_auxv, user_auxv, sizeof(user_auxv)); > task_unlock(current); > > return 0; > > base-commit: e43ffb69e0438cddd72aaa30898b4dc446f664f8