In the Linux kernel, the following vulnerability has been resolved:
cdrom: rearrange last_media_change check to avoid unintentional overflow
When running syzkaller with the newly reintroduced signed integer wrap
sanitizer we encounter this splat:
[ 366.015950] UBSAN: signed-integer-overflow in …/drivers/cdrom/cdrom.c:2361:33
[ 366.021089] -9223372036854775808 - 346321 cannot be represented in type ‘__s64’ (aka ‘long long’)
[ 366.025894] program syz-executor.4 is using a deprecated SCSI ioctl, please convert it to SG_IO
[ 366.027502] CPU: 5 PID: 28472 Comm: syz-executor.7 Not tainted 6.8.0-rc2-00035-gb3ef86b5a957 #1
[ 366.027512] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
[ 366.027518] Call Trace:
[ 366.027523] <TASK>
[ 366.027533] dump_stack_lvl+0x93/0xd0
[ 366.027899] handle_overflow+0x171/0x1b0
[ 366.038787] ata1.00: invalid multi_count 32 ignored
[ 366.043924] cdrom_ioctl+0x2c3f/0x2d10
[ 366.063932] ? __pm_runtime_resume+0xe6/0x130
[ 366.071923] sr_block_ioctl+0x15d/0x1d0
[ 366.074624] ? __pfx_sr_block_ioctl+0x10/0x10
[ 366.077642] blkdev_ioctl+0x419/0x500
[ 366.080231] ? __pfx_blkdev_ioctl+0x10/0x10
…
Historically, the signed integer overflow sanitizer did not work in the
kernel due to its interaction with -fwrapv
but this has since been
changed [1] in the newest version of Clang. It was re-enabled in the
kernel with Commit 557f8c582a9ba8ab (“ubsan: Reintroduce signed overflow
sanitizer”).
Let’s rearrange the check to not perform any arithmetic, thus not
tripping the sanitizer.
[
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "unaffected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"drivers/cdrom/cdrom.c"
],
"versions": [
{
"version": "1da177e4c3f4",
"lessThan": "0c97527e9160",
"status": "affected",
"versionType": "git"
},
{
"version": "1da177e4c3f4",
"lessThan": "3ee21e14c8c3",
"status": "affected",
"versionType": "git"
},
{
"version": "1da177e4c3f4",
"lessThan": "e809bc112712",
"status": "affected",
"versionType": "git"
},
{
"version": "1da177e4c3f4",
"lessThan": "efb905aeb44b",
"status": "affected",
"versionType": "git"
}
]
},
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "affected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"drivers/cdrom/cdrom.c"
],
"versions": [
{
"version": "6.1.98",
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "6.6.39",
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "6.9.9",
"lessThanOrEqual": "6.9.*",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "6.10",
"lessThanOrEqual": "*",
"status": "unaffected",
"versionType": "original_commit_for_fix"
}
]
}
]