In the Linux kernel, the following vulnerability has been resolved:
watch_queue: Fix filter limit check
In watch_queue_set_filter(), there are a couple of places where we check
that the filter type value does not exceed what the type_filter bitmap
can hold. One place calculates the number of bits by:
if (tf[i].type >= sizeof(wfilter->type_filter) * 8)
which is fine, but the second does:
if (tf[i].type >= sizeof(wfilter->type_filter) * BITS_PER_LONG)
which is not. This can lead to a couple of out-of-bounds writes due to
a too-large type:
(1) __set_bit() on wfilter->type_filter
(2) Writing more elements in wfilter->filters[] than we allocated.
Fix this by just using the proper WATCH_TYPE__NR instead, which is the
number of types we actually know about.
The bug may cause an oops looking something like:
BUG: KASAN: slab-out-of-bounds in watch_queue_set_filter+0x659/0x740
Write of size 4 at addr ffff88800d2c66bc by task watch_queue_oob/611
…
Call Trace:
<TASK>
dump_stack_lvl+0x45/0x59
print_address_description.constprop.0+0x1f/0x150
…
kasan_report.cold+0x7f/0x11b
…
watch_queue_set_filter+0x659/0x740
…
__x64_sys_ioctl+0x127/0x190
do_syscall_64+0x43/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae
Allocated by task 611:
kasan_save_stack+0x1e/0x40
__kasan_kmalloc+0x81/0xa0
watch_queue_set_filter+0x23a/0x740
__x64_sys_ioctl+0x127/0x190
do_syscall_64+0x43/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae
The buggy address belongs to the object at ffff88800d2c66a0
which belongs to the cache kmalloc-32 of size 32
The buggy address is located 28 bytes inside of
32-byte region [ffff88800d2c66a0, ffff88800d2c66c0)
[
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "unaffected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"include/linux/watch_queue.h",
"kernel/watch_queue.c"
],
"versions": [
{
"version": "c73be61cede5",
"lessThan": "648895da69ce",
"status": "affected",
"versionType": "git"
},
{
"version": "c73be61cede5",
"lessThan": "1b09f28f70a5",
"status": "affected",
"versionType": "git"
},
{
"version": "c73be61cede5",
"lessThan": "b36588ebbcef",
"status": "affected",
"versionType": "git"
},
{
"version": "c73be61cede5",
"lessThan": "c993ee0f9f81",
"status": "affected",
"versionType": "git"
}
]
},
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "affected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"include/linux/watch_queue.h",
"kernel/watch_queue.c"
],
"versions": [
{
"version": "5.8",
"status": "affected"
},
{
"version": "0",
"lessThan": "5.8",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "5.10.106",
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "5.15.29",
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "5.16.15",
"lessThanOrEqual": "5.16.*",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "5.17",
"lessThanOrEqual": "*",
"status": "unaffected",
"versionType": "original_commit_for_fix"
}
]
}
]