Messages in this thread | | | From | Jeffrin Thalakkottoor <> | Date | Tue, 30 Jul 2019 01:04:17 +0530 | Subject | Re: BUG: KASAN: global-out-of-bounds in ata_exec_internal_sg+0x50f/0xc70 |
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hello Kees Cook,
i tested your fix and i think it worked like a charm ! kasan message related disappeared during boot time and it does not show in the output of "sudo dmesg -l err" anyway thanks a lot !
On Fri, Jul 19, 2019 at 3:05 AM Kees Cook <keescook@chromium.org> wrote: > > On Tue, Jul 16, 2019 at 11:28:29AM -0700, Nick Desaulniers wrote: > > On Wed, Jul 10, 2019 at 10:44 AM Jeffrin Thalakkottoor > > <jeffrin@rajagiritech.edu.in> wrote: > > > > > > hello all , > > > > > > i encountered a KASAN bug related . here are some related information... > > > > > > > > > -------------------x-----------------------------x------------------ > > > [ 30.037312] BUG: KASAN: global-out-of-bounds in > > > ata_exec_internal_sg+0x50f/0xc70 > > > [ 30.037447] Read of size 16 at addr ffffffff91f41f80 by task scsi_eh_1/149 > > > > > > > > > [ 30.039935] The buggy address belongs to the variable: > > > [ 30.040059] cdb.48319+0x0/0x40 > > > (gdb) l *ata_exec_internal_sg+0x50f > > > 0xffffffff81c7b59f is in ata_exec_internal_sg (./include/linux/string.h:359). > > > > So looks like ata_exec_internal_sg() is panic'ing when... > > > > > 354 if (q_size < size) > > > 355 __read_overflow2(); > > > 356 } > > > 357 if (p_size < size || q_size < size) > > > 358 fortify_panic(__func__); > > > 359 return __builtin_memcpy(p, q, size); > > ^^^ here, so within memcpy(), but after the "easy" sanity checks. > > The only place where I see ata_exec_internal_sg() calling memcpy() is > here: > > /* prepare & issue qc */ > qc->tf = *tf; > if (cdb) > memcpy(qc->cdb, cdb, ATAPI_CDB_LEN); > > the "16" is consistent with the report: > > include/linux/ata.h: ATAPI_CDB_LEN = 16, > > which matches the claim about the cdb variable from KASAN. And it's a > read, so "cdb" is wrong. Do you have a longer back trace? What called > ata_exec_internal_sg()? > > ata_exec_internal() is the only caller of ata_exec_internal_sg(). Nearly > all callers of ata_exec_internal() pass a NULL cdb. Those that don't > are: > > atapi_eh_tur() > u8 cdb[ATAPI_CDB_LEN] = ... > atapi_eh_request_sense() > u8 cdb[ATAPI_CDB_LEN] = ... > > These two are on the static and correctly sized. > > eject_tray() > static const char cdb[ATAPI_CDB_LEN] = ... > zpodd_get_mech_type() > static const char cdb[] = ... > > These are both in rodata, and only the first is correctly sized. I > assume the following will fix it: > > > diff --git a/drivers/ata/libata-zpodd.c b/drivers/ata/libata-zpodd.c > index 173e6f2dd9af..eefda51f97d3 100644 > --- a/drivers/ata/libata-zpodd.c > +++ b/drivers/ata/libata-zpodd.c > @@ -56,7 +56,7 @@ static enum odd_mech_type zpodd_get_mech_type(struct ata_device *dev) > unsigned int ret; > struct rm_feature_desc *desc; > struct ata_taskfile tf; > - static const char cdb[] = { GPCMD_GET_CONFIGURATION, > + static const char cdb[ATAPI_CDB_LEN] = { GPCMD_GET_CONFIGURATION, > 2, /* only 1 feature descriptor requested */ > 0, 3, /* 3, removable medium feature */ > 0, 0, 0,/* reserved */ > > > > -- > Kees Cook
-- software engineer rajagiri school of engineering and technology
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