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From 0ad5340a73448535ca73d6e551955e2339c9e110 Mon Sep 17 00:00:00 2001
From: Max Reitz <>
Date: Mon, 15 Oct 2018 17:44:45 +0100
Subject: [PATCH 48/49] qemu-img: Fix assert when mapping unaligned raw file

RH-Author: Max Reitz <>
Message-id: <>
Patchwork-id: 82706
O-Subject: [RHEL-8 qemu-kvm PATCH v2 1/2] qemu-img: Fix assert when mapping unaligned raw file
Bugzilla: 1639374
RH-Acked-by: John Snow <>
RH-Acked-by: Kevin Wolf <>
RH-Acked-by: Thomas Huth <>

From: Eric Blake <>

Commit a290f085 exposed a latent bug in qemu-img map introduced
during the conversion of block status to be byte-based.  Earlier in
commit 5e344dd8, the internal interface get_block_status() switched
to take byte-based parameters, but still called a sector-based
block layer function; as such, rounding was added in the lone
caller to obey the contract.  However, commit 237d78f8 changed
get_block_status() to truly be byte-based, at which point rounding
to sector boundaries can result in calling bdrv_block_status() with
'bytes == 0' (a coding error) when the boundary between data and a
hole falls mid-sector (true for the past-EOF implicit hole present
in POSIX files).  Fix things by removing the rounding that is now
no longer necessary.

See also

Fixes: 237d78f8
Reported-by: Dan Kenigsberg <>
Reported-by: Nir Soffer <>
Reported-by: Maor Lipchuk <>
Signed-off-by: Eric Blake <>
Signed-off-by: Kevin Wolf <>
(cherry picked from commit e0b371ed5e2db079051139136fd0478728b6a58f)
Signed-off-by: Max Reitz <>
Signed-off-by: Danilo C. L. de Paula <>
 qemu-img.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/qemu-img.c b/qemu-img.c
index eaee6d6..b9bd401 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -2912,7 +2912,7 @@ static int img_map(int argc, char **argv)
         int64_t n;
         /* Probe up to 1 GiB at a time.  */
-        n = QEMU_ALIGN_DOWN(MIN(1 << 30, length - offset), BDRV_SECTOR_SIZE);
+        n = MIN(1 << 30, length - offset);
         ret = get_block_status(bs, offset, n, &next);
         if (ret < 0) {