Hello Nicolas,
On 21.06.22 16:04, Nicolas IOOSS wrote:
Hello,
I sent some days ago the vulnerability fix below. I have not received any reply yet. Could a maintainer take a look at it, please?
Sorry for that, but I was on the road (embedded world in nuremberg).
Best regards, Nicolas
------- Original Message ------- Le vendredi 10 juin 2022 à 4:50 PM, nicolas.iooss.ledger@proton.me a écrit :
From: Nicolas Iooss nicolas.iooss+uboot@ledger.fr
When running "i2c md 0 0 80000100", the function do_i2c_md parses the length into an unsigned int variable named length. The value is then moved to a signed variable:
int nbytes = length; #define DISP_LINE_LEN 16 int linebytes = (nbytes > DISP_LINE_LEN) ? DISP_LINE_LEN : nbytes;
ret = dm_i2c_read(dev, addr, linebuf, linebytes);
On systems where integers are 32 bits wide, 0x80000100 is a negative value to "nbytes > DISP_LINE_LEN" is false and linebytes gets assigned
0x80000100 instead of 16.
The consequence is that the function which reads from the i2c device (dm_i2c_read or i2c_read) is called with a 16-byte stack buffer to fill but with a size parameter which is too large. In some cases, this could trigger a crash. But with some i2c drivers, such as drivers/i2c/nx_i2c.c (used with "nexell,s5pxx18-i2c" bus), the size is actually truncated to a 16-bit integer. This is because function i2c_transfer expects an unsigned short length. In such a case, an attacker who can control the response of an i2c device can overwrite the return address of a function and execute arbitrary code through Return-Oriented Programming.
Fix this issue by using unsigned integers types in do_i2c_md. While at it, make also alen unsigned, as signed sizes can cause vulnerabilities when people forgot to check that they can be negative.
Signed-off-by: Nicolas Iooss nicolas.iooss+uboot@ledger.fr
cmd/i2c.c | 24 ++++++++++++------------ 1 file changed, 12 insertions(+), 12 deletions(-)
Reviewed-by: Heiko Schocher hs@denx.de
@Tom: Should we add this to 2022.07? If so, feel free to pick it up, thanks!
bye, Heiko