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zio: no alloc canary in userspace

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Makes it harder to use memory debuggers like valgrind directly, because
they can't see canary overruns.

Sponsored-by: Klara, Inc.
Sponsored-by: Wasabi Technology, Inc.
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rob Norris <rob.norris@klarasystems.com>
Closes #16253
This commit is contained in:
Rob Norris 2024-06-04 13:13:05 -04:00 committed by Brian Behlendorf
parent b3f4e4e1ec
commit 2b7d9a7863
1 changed files with 14 additions and 6 deletions
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20
module/zfs/zio.c
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@ -299,10 +299,13 @@ zio_fini(void)
* ==========================================================================
*/
#ifdef ZFS_DEBUG
static const ulong_t zio_buf_canary = (ulong_t)0xdeadc0dedead210b;
#if defined(ZFS_DEBUG) && defined(_KERNEL)
#define ZFS_ZIO_BUF_CANARY 1
#endif
#ifdef ZFS_ZIO_BUF_CANARY
static const ulong_t zio_buf_canary = (ulong_t)0xdeadc0dedead210b;
/*
* Use empty space after the buffer to detect overflows.
*
@ -314,7 +317,6 @@ static const ulong_t zio_buf_canary = (ulong_t)0xdeadc0dedead210b;
static void
zio_buf_put_canary(ulong_t *p, size_t size, kmem_cache_t **cache, size_t c)
{
#ifdef ZFS_DEBUG
size_t off = P2ROUNDUP(size, sizeof (ulong_t));
ulong_t *canary = p + off / sizeof (ulong_t);
size_t asize = (c + 1) << SPA_MINBLOCKSHIFT;
@ -323,13 +325,11 @@ zio_buf_put_canary(ulong_t *p, size_t size, kmem_cache_t **cache, size_t c)
asize = (c + 2) << SPA_MINBLOCKSHIFT;
for (; off < asize; canary++, off += sizeof (ulong_t))
*canary = zio_buf_canary;
#endif
}
static void
zio_buf_check_canary(ulong_t *p, size_t size, kmem_cache_t **cache, size_t c)
{
#ifdef ZFS_DEBUG
size_t off = P2ROUNDUP(size, sizeof (ulong_t));
ulong_t *canary = p + off / sizeof (ulong_t);
size_t asize = (c + 1) << SPA_MINBLOCKSHIFT;
@ -343,8 +343,8 @@ zio_buf_check_canary(ulong_t *p, size_t size, kmem_cache_t **cache, size_t c)
*canary, zio_buf_canary);
}
}
#endif
}
#endif
/*
* Use zio_buf_alloc to allocate ZFS metadata. This data will appear in a
@ -363,7 +363,9 @@ zio_buf_alloc(size_t size)
#endif
void *p = kmem_cache_alloc(zio_buf_cache[c], KM_PUSHPAGE);
#ifdef ZFS_ZIO_BUF_CANARY
zio_buf_put_canary(p, size, zio_buf_cache, c);
#endif
return (p);
}
@ -381,7 +383,9 @@ zio_data_buf_alloc(size_t size)
VERIFY3U(c, <, SPA_MAXBLOCKSIZE >> SPA_MINBLOCKSHIFT);
void *p = kmem_cache_alloc(zio_data_buf_cache[c], KM_PUSHPAGE);
#ifdef ZFS_ZIO_BUF_CANARY
zio_buf_put_canary(p, size, zio_data_buf_cache, c);
#endif
return (p);
}
@ -395,7 +399,9 @@ zio_buf_free(void *buf, size_t size)
atomic_add_64(&zio_buf_cache_frees[c], 1);
#endif
#ifdef ZFS_ZIO_BUF_CANARY
zio_buf_check_canary(buf, size, zio_buf_cache, c);
#endif
kmem_cache_free(zio_buf_cache[c], buf);
}
@ -406,7 +412,9 @@ zio_data_buf_free(void *buf, size_t size)
VERIFY3U(c, <, SPA_MAXBLOCKSIZE >> SPA_MINBLOCKSHIFT);
#ifdef ZFS_ZIO_BUF_CANARY
zio_buf_check_canary(buf, size, zio_data_buf_cache, c);
#endif
kmem_cache_free(zio_data_buf_cache[c], buf);
}