CVE-2024-39487

In the Linux kernel, the following vulnerability has been resolved:

bonding: Fix out-of-bounds read in bond_option_arp_ip_targets_set()

In function bond_option_arp_ip_targets_set(), if newval->string is an

empty string, newval->string+1 will point to the byte after the

string, causing an out-of-bound read.

BUG: KASAN: slab-out-of-bounds in strlen+0x7d/0xa0 lib/string.c:418

Read of size 1 at addr ffff8881119c4781 by task syz-executor665/8107

CPU: 1 PID: 8107 Comm: syz-executor665 Not tainted 6.7.0-rc7 #1

Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014

Call Trace:

<TASK>

__dump_stack lib/dump_stack.c:88 [inline]

dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106

print_address_description mm/kasan/report.c:364 [inline]

print_report+0xc1/0x5e0 mm/kasan/report.c:475

kasan_report+0xbe/0xf0 mm/kasan/report.c:588

strlen+0x7d/0xa0 lib/string.c:418

__fortify_strlen include/linux/fortify-string.h:210 [inline]

in4_pton+0xa3/0x3f0 net/core/utils.c:130

bond_option_arp_ip_targets_set+0xc2/0x910

drivers/net/bonding/bond_options.c:1201

__bond_opt_set+0x2a4/0x1030 drivers/net/bonding/bond_options.c:767

__bond_opt_set_notify+0x48/0x150 drivers/net/bonding/bond_options.c:792

bond_opt_tryset_rtnl+0xda/0x160 drivers/net/bonding/bond_options.c:817

bonding_sysfs_store_option+0xa1/0x120 drivers/net/bonding/bond_sysfs.c:156

dev_attr_store+0x54/0x80 drivers/base/core.c:2366

sysfs_kf_write+0x114/0x170 fs/sysfs/file.c:136

kernfs_fop_write_iter+0x337/0x500 fs/kernfs/file.c:334

call_write_iter include/linux/fs.h:2020 [inline]

new_sync_write fs/read_write.c:491 [inline]

vfs_write+0x96a/0xd80 fs/read_write.c:584

ksys_write+0x122/0x250 fs/read_write.c:637

do_syscall_x64 arch/x86/entry/common.c:52 [inline]

do_syscall_64+0x40/0x110 arch/x86/entry/common.c:83

entry_SYSCALL_64_after_hwframe+0x63/0x6b

---[ end trace ]---

Fix it by adding a check of string length before using it.