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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-43ce3f573f6sm15663895e9.0.2025.03.08.01.35.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 08 Mar 2025 01:35:15 -0800 (PST) From: David Laight To: linux-kernel@vger.kernel.org, Andrew Morton Cc: David Laight , Arnd Bergmann , Linus Torvalds , Christophe Leroy , Andy Shevchenko , Rasmus Villemoes , nnac123@linux.ibm.com, horms@kernel.org Subject: [PATCH next 4/8] test_hexdump: Check for buffer overrun of sample output buffer Date: Sat, 8 Mar 2025 09:34:48 +0000 Message-Id: <20250308093452.3742-5-david.laight.linux@gmail.com> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250308093452.3742-1-david.laight.linux@gmail.com> References: <20250308093452.3742-1-david.laight.linux@gmail.com> 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" While the output generated by test_hexdump_prepare_test() shouldn't be longer than the size of the buffer passed, for safety verify that the buffer is long enough. If too short fill the buffer with an error message - output on test failure. Signed-off-by: David Laight --- lib/test_hexdump.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/lib/test_hexdump.c b/lib/test_hexdump.c index 743ea5c78f9e..ed6f0b0a1bb3 100644 --- a/lib/test_hexdump.c +++ b/lib/test_hexdump.c @@ -39,6 +39,14 @@ static size_t __init test_hexdump_prepare_test(size_t le= n, size_t rowsize, groupsize =3D 1; byteswap =3D IS_ENABLED(CONFIG_CPU_BIG_ENDIAN) ? 0 : groupsize - 1; =20 + /* Check test passed a big enough output buffer */ + if (ascii) + i =3D rowsize * 2 + rowsize / groupsize + 1 + len + 1; + else + i =3D len * 2 + len / groupsize - 1 + 1; + if (i > testlen) + return scnprintf(test, testlen, "buffer too short %zu < %zu", testlen, i= ); + /* hex dump */ p =3D test; for (i =3D 0, j =3D 0; i < len; i++) { --=20 2.39.5