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([108.180.130.139]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-38e4aff383dsm3129270a91.8.2026.07.18.11.22.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 18 Jul 2026 11:22:37 -0700 (PDT) From: Babanpreet Singh To: Jonathan Cameron Cc: =?UTF-8?q?Nuno=20S=C3=A1?= , Michael Hennerich , David Lechner , Andy Shevchenko , Andy Shevchenko , Angelo Dureghello , linux@analog.com, linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, Babanpreet Singh Subject: [PATCH v3] iio: dac: ad3552r-hs: fix scnprintf() buffer bound in data source show Date: Sat, 18 Jul 2026 18:22:36 +0000 Message-ID: <20260718182236.7-1-bbnpreetsingh@gmail.com> X-Mailer: git-send-email 2.47.3 Precedence: bulk X-Mailing-List: linux-iio@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit ad3552r_hs_show_data_source_avail() formats the available data source names into a 128-byte stack buffer, but bounds each scnprintf() with PAGE_SIZE instead of the buffer size, so the bound does not protect the destination at all. This cannot overflow today - dbgfs_attr_source[] has two entries, "normal" and "ramp-16bit", 18 bytes formatted - but the bound stops protecting the stack the day the table grows. Use sizeof(buf) so the bound matches the destination. Found by smatch: drivers/iio/dac/ad3552r-hs.c:593 ad3552r_hs_show_data_source_avail() error: scnprintf() 'buf[len]' too small (128 vs 4096) Fixes: b1c5d68ea66e ("iio: dac: ad3552r-hs: add support for internal ramp") Assisted-by: Claude:claude-sonnet-5 Signed-off-by: Babanpreet Singh --- v3: - Return to the v1 fix: bound scnprintf() with sizeof(buf) instead of switching to sysfs_emit_at(). As Andy noticed in the v2 review, this is a custom debugfs read handler formatting a kernel buffer for simple_read_from_buffer(), not a sysfs show callback, so sysfs_emit_at() does not apply here: https://lore.kernel.org/r/als6lRi-H4DM7ra6@ashevche-desk.local - Dropped Suggested-by and restored the v1 title; the diff is identical to v1. v2: https://lore.kernel.org/r/20260718044244.7-1-bbnpreetsingh@gmail.com v1: https://lore.kernel.org/r/20260717040024.7-1-bbnpreetsingh@gmail.com drivers/iio/dac/ad3552r-hs.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/iio/dac/ad3552r-hs.c b/drivers/iio/dac/ad3552r-hs.c index 02a124ac4855..f865843aa439 100644 --- a/drivers/iio/dac/ad3552r-hs.c +++ b/drivers/iio/dac/ad3552r-hs.c @@ -590,7 +590,7 @@ static ssize_t ad3552r_hs_show_data_source_avail(struct file *f, int i; for (i = 0; i < ARRAY_SIZE(dbgfs_attr_source); i++) { - len += scnprintf(buf + len, PAGE_SIZE - len, "%s ", + len += scnprintf(buf + len, sizeof(buf) - len, "%s ", dbgfs_attr_source[i]); } buf[len - 1] = '\n'; base-commit: fce2dfa773ced15f27dd27cd0b482a7473cdcf2a -- 2.43.0