On Tue, Mar 16, 2021 at 04:44:45PM +0100, Arnd Bergmann wrote: > On Tue, Mar 16, 2021 at 11:17 AM Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote: > > On Tue, Mar 16, 2021 at 11:02 AM Arnd Bergmann <arnd@xxxxxxxx> wrote: > > > > On Tue, Mar 16, 2021 at 8:18 AM syzbot > > > > > > > [<8073772c>] (integrity_kernel_read) from [<8073a904>] (ima_calc_file_hash_tfm+0x178/0x228 security/integrity/ima/ima_crypto.c:484) > > > > > [<8073a78c>] (ima_calc_file_hash_tfm) from [<8073ae2c>] (ima_calc_file_shash security/integrity/ima/ima_crypto.c:515 [inline]) > > > > > [<8073a78c>] (ima_calc_file_hash_tfm) from [<8073ae2c>] (ima_calc_file_hash+0x124/0x8b8 security/integrity/ima/ima_crypto.c:572) > > > > > > ima_calc_file_hash_tfm() has a SHASH_DESC_ON_STACK(), which by itself can > > > use up 512 bytes, but KASAN sometimes triples this number. However, I see > > > you do not actually have KASAN enabled, so there is probably more to it. > > > > The compiler is gcc version 10.2.1 20210110 (Debian 10.2.1-6) > > Ok, building with Ubuntu 10.2.1-1ubuntu1 20201207 locally, that's > the closest I have installed, and I think the Debian and Ubuntu versions > are generally quite close in case of gcc since they are maintained by > the same packagers. > > I see ima_calc_field_array_hash_tfm() shows up as one of the larger > stack users, but not alarmingly high: > ../security/integrity/ima/ima_crypto.c: In function > ‘ima_calc_field_array_hash_tfm’: > ../security/integrity/ima/ima_crypto.c:624:1: warning: the frame size > of 664 bytes is larger than 600 bytes [-Wframe-larger-than=] > none of the other functions from the call chain have more than 600 bytes > in this combination of config/compiler/sourcetree. > > In combination, I don't get to more than ~2300 bytes: ... which shouldn't be a problem - that's just over 1/4 of the stack space. Could it be the syzbot's gcc is doing something weird and inflating the stack frames? -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
