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Wysocki (Intel)" , stable@vger.kernel.org Subject: [PATCH v2 16/51] PNP: isapnp: don't read past the end of the buffer on a large pread() Date: Wed, 4 Nov 2026 18:47:02 +0100 Message-ID: <20261104-work-procfs-bugfixes-v2-16-bbf7d5546809@kernel.org> In-Reply-To: <20261104-work-procfs-bugfixes-v2-0-bbf7d5546809@kernel.org> References: <20261104-work-procfs-bugfixes-v2-0-bbf7d5546809@kernel.org> X-Mailing-List: linux-serial@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" X-Mailer: b4 0.17-dev X-Developer-Signature: v=1; a=openpgp-sha256; l=1354; i=brauner@kernel.org; h=from:subject:message-id; bh=PRZX3tU6vm07qtbuZVgSHwh1cNhLueRVjGfMu08d6P4=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWS9zrtUYRVq+tJ15s3yZb8YE8ruM70T7nORa7gzVYHp6 IWYiau+dZSyMIhxMciKKbI4tJuEyy3nqdhslKkBM4eVCWQIAxenAExkayzDP437H9oT5hamvooK OVxRlmLxXWH+GcXu85dCX7799vrxjHCG/1VvHrytuewz1X2zy+xnicIPZ+XMqNI6IcTmwLa42Wc DJzcA X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 Content-Transfer-Encoding: 8bit isapnp_proc_bus_read() truncates the position to an int. A pread() at an offset like 0xfffffc00 turns it negative, the check against the size of the configuration space passes, and the loop then puts everything from that position up to byte 256 into the reader's buffer, no matter how few bytes were asked for. Keep the position as a loff_t and clamp the count against what is left of the configuration space. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reviewed-by: Rafael J. Wysocki (Intel) Cc: stable@vger.kernel.org Signed-off-by: Christian Brauner (Amutable) --- drivers/pnp/isapnp/proc.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/drivers/pnp/isapnp/proc.c b/drivers/pnp/isapnp/proc.c index b3abab24050b..1829c20d5446 100644 --- a/drivers/pnp/isapnp/proc.c +++ b/drivers/pnp/isapnp/proc.c @@ -23,15 +23,13 @@ static ssize_t isapnp_proc_bus_read(struct file *file, char __user * buf, size_t nbytes, loff_t * ppos) { struct pnp_dev *dev = pde_data(file_inode(file)); - int pos = *ppos; + loff_t pos = *ppos; int cnt, size = 256; int ret; if (pos >= size) return 0; - if (nbytes >= size) - nbytes = size; - if (pos + nbytes > size) + if (nbytes > size - pos) nbytes = size - pos; cnt = nbytes; -- 2.53.0