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authorSilvio Cesare <silvio.cesare@gmail.com>2019-01-15 06:27:27 +0300
committerMark Brown <broonie@kernel.org>2019-01-15 22:06:08 +0300
commitc407cd008fd039320d147088b52d0fa34ed3ddcb (patch)
tree3a1d627df42547bfb0036911eccdd73514d73b66
parent060d0bf491874daece47053c4e1fb0489eb867d2 (diff)
downloadlinux-c407cd008fd039320d147088b52d0fa34ed3ddcb.tar.xz
ASoC: imx-audmux: 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: Timur Tabi <timur@kernel.org> Cc: Nicolin Chen <nicoleotsuka@gmail.com> Cc: Mark Brown <broonie@kernel.org> Cc: Xiubo Li <Xiubo.Lee@gmail.com> Cc: Fabio Estevam <fabio.estevam@nxp.com> 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> Acked-by: Nicolin Chen <nicoleotsuka@gmail.com> Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Mark Brown <broonie@kernel.org>
-rw-r--r--sound/soc/fsl/imx-audmux.c24
1 files changed, 12 insertions, 12 deletions
diff --git a/sound/soc/fsl/imx-audmux.c b/sound/soc/fsl/imx-audmux.c
index 392d5eef356d..99e07b01a2ce 100644
--- a/sound/soc/fsl/imx-audmux.c
+++ b/sound/soc/fsl/imx-audmux.c
@@ -86,49 +86,49 @@ static ssize_t audmux_read_file(struct file *file, char __user *user_buf,
if (!buf)
return -ENOMEM;
- ret = snprintf(buf, PAGE_SIZE, "PDCR: %08x\nPTCR: %08x\n",
+ ret = scnprintf(buf, PAGE_SIZE, "PDCR: %08x\nPTCR: %08x\n",
pdcr, ptcr);
if (ptcr & IMX_AUDMUX_V2_PTCR_TFSDIR)
- ret += snprintf(buf + ret, PAGE_SIZE - ret,
+ ret += scnprintf(buf + ret, PAGE_SIZE - ret,
"TxFS output from %s, ",
audmux_port_string((ptcr >> 27) & 0x7));
else
- ret += snprintf(buf + ret, PAGE_SIZE - ret,
+ ret += scnprintf(buf + ret, PAGE_SIZE - ret,
"TxFS input, ");
if (ptcr & IMX_AUDMUX_V2_PTCR_TCLKDIR)
- ret += snprintf(buf + ret, PAGE_SIZE - ret,
+ ret += scnprintf(buf + ret, PAGE_SIZE - ret,
"TxClk output from %s",
audmux_port_string((ptcr >> 22) & 0x7));
else
- ret += snprintf(buf + ret, PAGE_SIZE - ret,
+ ret += scnprintf(buf + ret, PAGE_SIZE - ret,
"TxClk input");
- ret += snprintf(buf + ret, PAGE_SIZE - ret, "\n");
+ ret += scnprintf(buf + ret, PAGE_SIZE - ret, "\n");
if (ptcr & IMX_AUDMUX_V2_PTCR_SYN) {
- ret += snprintf(buf + ret, PAGE_SIZE - ret,
+ ret += scnprintf(buf + ret, PAGE_SIZE - ret,
"Port is symmetric");
} else {
if (ptcr & IMX_AUDMUX_V2_PTCR_RFSDIR)
- ret += snprintf(buf + ret, PAGE_SIZE - ret,
+ ret += scnprintf(buf + ret, PAGE_SIZE - ret,
"RxFS output from %s, ",
audmux_port_string((ptcr >> 17) & 0x7));
else
- ret += snprintf(buf + ret, PAGE_SIZE - ret,
+ ret += scnprintf(buf + ret, PAGE_SIZE - ret,
"RxFS input, ");
if (ptcr & IMX_AUDMUX_V2_PTCR_RCLKDIR)
- ret += snprintf(buf + ret, PAGE_SIZE - ret,
+ ret += scnprintf(buf + ret, PAGE_SIZE - ret,
"RxClk output from %s",
audmux_port_string((ptcr >> 12) & 0x7));
else
- ret += snprintf(buf + ret, PAGE_SIZE - ret,
+ ret += scnprintf(buf + ret, PAGE_SIZE - ret,
"RxClk input");
}
- ret += snprintf(buf + ret, PAGE_SIZE - ret,
+ ret += scnprintf(buf + ret, PAGE_SIZE - ret,
"\nData received from %s\n",
audmux_port_string((pdcr >> 13) & 0x7));