media: dvb-usb: az6027: fix null-ptr-deref in az6027_i2c_xfer()

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: media: dvb-usb: az6027: fix null-ptr-deref in az6027_i2c_xfer() Wei Chen reports a kernel bug as blew: general protection fault, probably for non-canonical address KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017] ... Call Trace: <TASK> __i2c_transfer+0x77e/0x1930 drivers/i2c/i2c-core-base.c:2109 i2c_transfer+0x1d5/0x3d0 drivers/i2c/i2c-core-base.c:2170 i2cdev_ioctl_rdwr+0x393/0x660 drivers/i2c/i2c-dev.c:297 i2cdev_ioctl+0x75d/0x9f0 drivers/i2c/i2c-dev.c:458 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl+0xfb/0x170 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7fd834a8bded In az6027_i2c_xfer(), if msg[i].addr is 0x99, a null-ptr-deref will caused when accessing msg[i].buf. For msg[i].len is 0 and msg[i].buf is null. Fix this by checking msg[i].len in az6027_i2c_xfer().

References

• https://git.kernel.org/stable/c/2b6a8a1a32746981044e7ab06649c804acb4068a
• https://git.kernel.org/stable/c/c712d1ccbfb787620422b437a5b8fac0802547bd
• https://git.kernel.org/stable/c/7abfe467cd685f5da7ecb415441e45e3e4e2baa8
• https://git.kernel.org/stable/c/8b256d23361c51aa4b7fdb71176c1ca50966fb39
• https://git.kernel.org/stable/c/559891d430e3f3a178040c4371ed419edbfa7d65
• https://git.kernel.org/stable/c/210fcf64be4db82c0e190e74b5111e4eef661a7a
• https://git.kernel.org/stable/c/6fbc44731a4665cbe92a5090e9804a388a72214b
• https://git.kernel.org/stable/c/6b60cf73a931af34b7a0a3f467a79d9fe0df2d70
• https://git.kernel.org/stable/c/0ed554fd769a19ea8464bb83e9ac201002ef74ad