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Ido Schimmel authored
Both ip_neigh_gw4() and ip_neigh_gw6() can return either a valid pointer or an error pointer, but the code currently checks that the pointer is not NULL. Fix this by checking that the pointer is not an error pointer, as this can result in a NULL pointer dereference [1]. Specifically, I believe that what happened is that ip_neigh_gw4() returned '-EINVAL' (0xffffffffffffffea) to which the offset of 'refcnt' (0x70) was added, which resulted in the address 0x000000000000005a. [1] BUG: KASAN: null-ptr-deref in refcount_inc_not_zero_checked+0x6e/0x180 Read of size 4 at addr 000000000000005a by task swapper/2/0 CPU: 2 PID: 0 Comm: swapper/2 Not tainted 5.2.0-rc6-custom-reg-179657-gaa32d89 #396 Hardware name: Mellanox Technologies Ltd. MSN2010/SA002610, BIOS 5.6.5 08/24/2017 Call Trace: <IRQ> dump_stack+0x73/0xbb __kasan_report+0x188/0x1ea kasan_report+0xe/0x20 refcount_inc_not_zero_checked+0x6e/0x180 ipv4_neigh_lookup+0x365/0x12c0 __neigh_u...
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