The patch

ASoC: dapm: change snprintf to scnprintf for possible overflow

has been applied to the asoc tree at

https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git

All being well this means that it will be integrated into the linux-next tree (usually sometime in the next 24 hours) and sent to Linus during the next merge window (or sooner if it is a bug fix), however if problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing and review of the tree, please engage with people reporting problems and send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they should be sent as incremental updates against current git, existing patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying to this mail.

Thanks, Mark

From e581e151e965bf1f2815dd94620b638fec4d0a7e Mon Sep 17 00:00:00 2001

From: Silvio Cesare silvio.cesare@gmail.com Date: Sat, 12 Jan 2019 16:28:43 +0100 Subject: [PATCH] ASoC: dapm: change snprintf to scnprintf for possible overflow

Change snprintf to scnprintf. There are generally two cases where using snprintf causes problems.

1) Uses of size += snprintf(buf, SIZE - size, fmt, ...) In this case, if snprintf would have written more characters than what the buffer size (SIZE) is, then size will end up larger than SIZE. In later uses of snprintf, SIZE - size will result in a negative number, leading to problems. Note that size might already be too large by using size = snprintf before the code reaches a case of size += snprintf.

2) If size is ultimately used as a length parameter for a copy back to user space, then it will potentially allow for a buffer overflow and information disclosure when size is greater than SIZE. When the size is used to index the buffer directly, we can have memory corruption. This also means when size = snprintf... is used, it may also cause problems since size may become large. Copying to userspace is mitigated by the HARDENED_USERCOPY kernel configuration.

The solution to these issues is to use scnprintf which returns the number of characters actually written to the buffer, so the size variable will never exceed SIZE.

Signed-off-by: Silvio Cesare silvio.cesare@gmail.com Cc: Liam Girdwood lgirdwood@gmail.com Cc: Mark Brown broonie@kernel.org Cc: Dan Carpenter dan.carpenter@oracle.com Cc: Kees Cook keescook@chromium.org Cc: Will Deacon will.deacon@arm.com Cc: Greg KH greg@kroah.com Signed-off-by: Willy Tarreau w@1wt.eu Signed-off-by: Mark Brown broonie@kernel.org --- sound/soc/soc-dapm.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/sound/soc/soc-dapm.c b/sound/soc/soc-dapm.c index a5178845065b..2c4c13419539 100644 --- a/sound/soc/soc-dapm.c +++ b/sound/soc/soc-dapm.c @@ -2019,19 +2019,19 @@ static ssize_t dapm_widget_power_read_file(struct file *file, out = is_connected_output_ep(w, NULL, NULL); }

- ret = snprintf(buf, PAGE_SIZE, "%s: %s%s in %d out %d", + ret = scnprintf(buf, PAGE_SIZE, "%s: %s%s in %d out %d", w->name, w->power ? "On" : "Off", w->force ? " (forced)" : "", in, out);

if (w->reg >= 0) - ret += snprintf(buf + ret, PAGE_SIZE - ret, + ret += scnprintf(buf + ret, PAGE_SIZE - ret, " - R%d(0x%x) mask 0x%x", w->reg, w->reg, w->mask << w->shift);

- ret += snprintf(buf + ret, PAGE_SIZE - ret, "\n"); + ret += scnprintf(buf + ret, PAGE_SIZE - ret, "\n");

if (w->sname) - ret += snprintf(buf + ret, PAGE_SIZE - ret, " stream %s %s\n", + ret += scnprintf(buf + ret, PAGE_SIZE - ret, " stream %s %s\n", w->sname, w->active ? "active" : "inactive");

@@ -2044,7 +2044,7 @@ static ssize_t dapm_widget_power_read_file(struct file *file, if (!p->connect) continue;

- ret += snprintf(buf + ret, PAGE_SIZE - ret, + ret += scnprintf(buf + ret, PAGE_SIZE - ret, " %s "%s" "%s"\n", (rdir == SND_SOC_DAPM_DIR_IN) ? "in" : "out", p->name ? p->name : "static",