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Fri, 25 Sep 2026 18:26:59 -0700 (PDT) Received: from FT6N242TWK ([223.181.117.160]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-341f2b18cbfsm6746171eec.30.2026.09.25.18.26.56 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Fri, 25 Sep 2026 18:26:58 -0700 (PDT) From: Shashank Mohan Jain To: Yury Norov Cc: Rasmus Villemoes , Andrew Morton , linux-kernel@vger.kernel.org Subject: [PATCH v2 1/6] bitmap: bitmap_parse(): reject non-hex character before 8 digits Date: Sat, 26 Sep 2026 06:56:46 +0530 Message-ID: <20260926012651.15524-2-jain.sm@gmail.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260926012651.15524-1-jain.sm@gmail.com> References: <20260926012651.15524-1-jain.sm@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: 8bit bitmap_parse() is documented to return -EINVAL for illegal characters, and it does so everywhere except when the illegal character directly precedes a chunk of exactly eight hex digits. bitmap_get_x32_reverse() parses a chunk from right to left. After it has consumed eight digits it looks at one more character: a hex digit means the chunk is wider than 32 bits and -EOVERFLOW is returned. Any other character is silently consumed as if it were a separator, and the remaining input is parsed as the next chunk. As a result: "x12345678" -> 0x12345678, returns 0 (expected -EINVAL) "1g12345678" -> 0x1_12345678, returns 0 (expected -EINVAL) "0x0000000f" -> 0xf, returns 0, while "0xf" returns -EINVAL bitmap_parse() backs cpumask_parse() and cpumask_parse_user(), so the same inconsistency is visible when writing masks such as /proc/irq/*/smp_affinity or the network queue rps_cpus/xps_cpus files. __bitmap_parse(), which this function replaced in commit 2d6261583be0 ("lib: rework bitmap_parse()"), rejected all three strings with -EINVAL, and a "0x" prefix is accepted today only when exactly eight digits follow it, so no reliably working input is lost. When the loop falls through, *end is known to be a non-separator character inside the buffer, so return -EOVERFLOW if it is a hex digit and -EINVAL otherwise. Fixes: 2d6261583be0 ("lib: rework bitmap_parse()") Assisted-by: LLM Signed-off-by: Shashank Mohan Jain --- lib/bitmap-str.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/lib/bitmap-str.c b/lib/bitmap-str.c index dd9aa0635fa5..e02c5bc80951 100644 --- a/lib/bitmap-str.c +++ b/lib/bitmap-str.c @@ -414,8 +414,12 @@ static const char *bitmap_get_x32_reverse(const char *start, goto out; } - if (hex_to_bin(*end--) >= 0) - return ERR_PTR(-EOVERFLOW); + /* + * Eight digits have been consumed and the next character is not a + * separator: another hex digit means the chunk does not fit in 32 + * bits, anything else is an illegal character. + */ + return ERR_PTR(hex_to_bin(*end) >= 0 ? -EOVERFLOW : -EINVAL); out: *num = ret; return end; -- 2.43.0