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Fri, 25 Sep 2026 18:27:04 -0700 (PDT) Received: from FT6N242TWK ([223.181.117.160]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-341f2b18cbfsm6746171eec.30.2026.09.25.18.27.02 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Fri, 25 Sep 2026 18:27:03 -0700 (PDT) From: Shashank Mohan Jain To: Yury Norov Cc: Rasmus Villemoes , Andrew Morton , linux-kernel@vger.kernel.org Subject: [PATCH v2 3/6] bitmap: bitmap_parselist(): reject trailing characters after group size Date: Sat, 26 Sep 2026 06:56:48 +0530 Message-ID: <20260926012651.15524-4-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_region() checks that every region ends at a separator (',', whitespace, '\n' or '\0'), except in the "range:used/group" form: after parsing the group size it returns the pointer to the following character without looking at it. The caller then starts a new region at that character. Before 'N' and 'all' were accepted as region starts this happened to be harmless, because any other character would fail to parse as a new region. Now text directly following the group size is silently parsed as another region: "0-7:1/2N" -> bits 0,2,4,6,7 (nbits = 8), returns 0 "0-7:1/2all" -> all bits set, returns 0 while "0-7N", "5N" or "0-7:1/2x" are correctly rejected with -EINVAL. bitmap_parselist() is documented to return -EINVAL for an invalid character. It parses cpu lists from sysfs, cgroup cpuset files and boot parameters such as isolcpus= and nohz_full=, so a typo there is accepted and yields a different mask than intended. Check for the end of the region after the group size as well, like the other forms do. Fixes: 2c4885d24e64 ("lib: bitmap: support "N" as an alias for size of bitmap") Assisted-by: LLM Signed-off-by: Shashank Mohan Jain --- lib/bitmap-str.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/lib/bitmap-str.c b/lib/bitmap-str.c index e02c5bc80951..b58966864657 100644 --- a/lib/bitmap-str.c +++ b/lib/bitmap-str.c @@ -299,7 +299,14 @@ static const char *bitmap_parse_region(const char *str, struct region *r) if (*str != '/') return ERR_PTR(-EINVAL); - return bitmap_getnum(str + 1, &r->group_len, lastbit); + str = bitmap_getnum(str + 1, &r->group_len, lastbit); + if (IS_ERR(str)) + return str; + + if (!end_of_region(*str)) + return ERR_PTR(-EINVAL); + + return end_of_str(*str) ? NULL : str; no_end: r->end = r->start; -- 2.43.0