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fix: Shift exponent too large

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Undefined operation is reported by running ztest (or zloop) compiled with GCC
UndefinedBehaviorSanitizer. Error only happens on top level of dnode indirection
with large enough offset values. Logically, left shift operation would work,
but bit shift semantics in C, and limitation of uint64_t, do not produce desired
result.

Issue #5059, #4883

Signed-off-by: Gvozden Neskovic <neskovic@gmail.com>
This commit is contained in:
Gvozden Neskovic 2016-08-31 10:12:08 +02:00 committed by Brian Behlendorf
parent 0b78aeae92
commit 031d7c2fe6
5 changed files with 38 additions and 9 deletions
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3
include/sys/dbuf.h
View File

@ -270,7 +270,8 @@ typedef struct dbuf_hash_table {
kmutex_t hash_mutexes[DBUF_MUTEXES];
} dbuf_hash_table_t;
uint64_t dbuf_whichblock(struct dnode *di, int64_t level, uint64_t offset);
uint64_t dbuf_whichblock(const struct dnode *di, const int64_t level,
const uint64_t offset);
void dbuf_create_bonus(struct dnode *dn);
int dbuf_spill_set_blksz(dmu_buf_t *db, uint64_t blksz, dmu_tx_t *tx);

5
include/sys/dnode.h
View File

@ -104,9 +104,8 @@ extern "C" {
#define DNODES_PER_LEVEL_SHIFT (DN_MAX_INDBLKSHIFT - SPA_BLKPTRSHIFT)
#define DNODES_PER_LEVEL (1ULL << DNODES_PER_LEVEL_SHIFT)
/* The +2 here is a cheesy way to round up */
#define DN_MAX_LEVELS (2 + ((DN_MAX_OFFSET_SHIFT - SPA_MINBLOCKSHIFT) / \
(DN_MIN_INDBLKSHIFT - SPA_BLKPTRSHIFT)))
#define DN_MAX_LEVELS (DIV_ROUND_UP(DN_MAX_OFFSET_SHIFT - SPA_MINBLOCKSHIFT, \
DN_MIN_INDBLKSHIFT - SPA_BLKPTRSHIFT) + 1)
#define DN_BONUS(dnp) ((void*)((dnp)->dn_bonus + \
(((dnp)->dn_nblkptr - 1) * sizeof (blkptr_t))))

3
lib/libspl/include/sys/sysmacros.h
View File

@ -42,6 +42,9 @@
#ifndef ARRAY_SIZE
#define ARRAY_SIZE(a) (sizeof (a) / sizeof (a[0]))
#endif
#ifndef DIV_ROUND_UP
#define DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d))
#endif
#define makedevice(maj, min) makedev(maj, min)
#define _sysconf(a) sysconf(a)

17
module/zfs/dbuf.c
View File

@ -918,7 +918,7 @@ dbuf_loan_arcbuf(dmu_buf_impl_t *db)
* provided.
*/
uint64_t
dbuf_whichblock(dnode_t *dn, int64_t level, uint64_t offset)
dbuf_whichblock(const dnode_t *dn, const int64_t level, const uint64_t offset)
{
if (dn->dn_datablkshift != 0 && dn->dn_indblkshift != 0) {
/*
@ -940,8 +940,19 @@ dbuf_whichblock(dnode_t *dn, int64_t level, uint64_t offset)
* = offset >> (datablkshift + level *
* (indblkshift - SPA_BLKPTRSHIFT))
*/
return (offset >> (dn->dn_datablkshift + level *
(dn->dn_indblkshift - SPA_BLKPTRSHIFT)));
const unsigned exp = dn->dn_datablkshift +
level * (dn->dn_indblkshift - SPA_BLKPTRSHIFT);
if (exp >= 8 * sizeof (offset)) {
/* This only happens on the highest indirection level */
ASSERT3U(level, ==, dn->dn_nlevels - 1);
return (0);
}
ASSERT3U(exp, <, 8 * sizeof (offset));
return (offset >> exp);
} else {
ASSERT3U(offset, <, dn->dn_datablksz);
return (0);

19
module/zfs/dnode.c
View File

@ -1612,6 +1612,8 @@ dnode_new_blkid(dnode_t *dn, uint64_t blkid, dmu_tx_t *tx, boolean_t have_read)
sz <= blkid && sz >= dn->dn_nblkptr; sz <<= epbs)
new_nlevels++;
ASSERT3U(new_nlevels, <=, DN_MAX_LEVELS);
if (new_nlevels > dn->dn_nlevels) {
int old_nlevels = dn->dn_nlevels;
dmu_buf_impl_t *db;
@ -2073,7 +2075,14 @@ dnode_next_offset_level(dnode_t *dn, int flags, uint64_t *offset,
else
minfill++;
*offset = *offset >> span;
if (span >= 8 * sizeof (*offset)) {
/* This only happens on the highest indirection level */
ASSERT3U((lvl - 1), ==, dn->dn_phys->dn_nlevels - 1);
*offset = 0;
} else {
*offset = *offset >> span;
}
for (i = BF64_GET(*offset, 0, epbs);
i >= 0 && i < epb; i += inc) {
if (BP_GET_FILL(&bp[i]) >= minfill &&
@ -2083,7 +2092,13 @@ dnode_next_offset_level(dnode_t *dn, int flags, uint64_t *offset,
if (inc > 0 || *offset > 0)
*offset += inc;
}
*offset = *offset << span;
if (span >= 8 * sizeof (*offset)) {
*offset = start;
} else {
*offset = *offset << span;
}
if (inc < 0) {
/* traversing backwards; position offset at the end */
ASSERT3U(*offset, <=, start);