* [PATCH] btrfs: avoid "used uninitialized" error with GCC7
@ 2017-03-31 16:42 Andrei Borzenkov
2017-04-03 8:59 ` Vladimir 'phcoder' Serbinenko
0 siblings, 1 reply; 3+ messages in thread
From: Andrei Borzenkov @ 2017-03-31 16:42 UTC (permalink / raw)
To: grub-devel
sblock was local and so considered new variable on every loop
iteration.
While on it, dynamically allocate buffer to reduce stack usage.
Closes: 50597
---
grub-core/fs/btrfs.c | 18 ++++++++++++------
1 file changed, 12 insertions(+), 6 deletions(-)
diff --git a/grub-core/fs/btrfs.c b/grub-core/fs/btrfs.c
index 9cffa91..99e81f9 100644
--- a/grub-core/fs/btrfs.c
+++ b/grub-core/fs/btrfs.c
@@ -229,24 +229,29 @@ read_sblock (grub_disk_t disk, struct grub_btrfs_superblock *sb)
{
unsigned i;
grub_err_t err = GRUB_ERR_NONE;
+ struct grub_btrfs_superblock *sblock;
+
+ sblock = grub_malloc (sizeof (*sblock));
+ if (sblock == NULL)
+ return grub_errno;
+
for (i = 0; i < ARRAY_SIZE (superblock_sectors); i++)
{
- struct grub_btrfs_superblock sblock;
/* Don't try additional superblocks beyond device size. */
- if (i && (grub_le_to_cpu64 (sblock.this_device.size)
+ if (i && (grub_le_to_cpu64 (sblock->this_device.size)
>> GRUB_DISK_SECTOR_BITS) <= superblock_sectors[i])
break;
err = grub_disk_read (disk, superblock_sectors[i], 0,
- sizeof (sblock), &sblock);
+ sizeof (*sblock), sblock);
if (err == GRUB_ERR_OUT_OF_RANGE)
break;
- if (grub_memcmp ((char *) sblock.signature, GRUB_BTRFS_SIGNATURE,
+ if (grub_memcmp ((char *) sblock->signature, GRUB_BTRFS_SIGNATURE,
sizeof (GRUB_BTRFS_SIGNATURE) - 1) != 0)
break;
- if (i == 0 || grub_le_to_cpu64 (sblock.generation)
+ if (i == 0 || grub_le_to_cpu64 (sblock->generation)
> grub_le_to_cpu64 (sb->generation))
- grub_memcpy (sb, &sblock, sizeof (sblock));
+ grub_memcpy (sb, sblock, sizeof (*sblock));
}
if ((err == GRUB_ERR_OUT_OF_RANGE || !err) && i == 0)
@@ -255,6 +260,7 @@ read_sblock (grub_disk_t disk, struct grub_btrfs_superblock *sb)
if (err == GRUB_ERR_OUT_OF_RANGE)
grub_errno = err = GRUB_ERR_NONE;
+ grub_free (sblock);
return err;
}
--
tg: (8014b7b..) bug/50597 (depends on: master)
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] btrfs: avoid "used uninitialized" error with GCC7
2017-03-31 16:42 [PATCH] btrfs: avoid "used uninitialized" error with GCC7 Andrei Borzenkov
@ 2017-04-03 8:59 ` Vladimir 'phcoder' Serbinenko
2017-04-04 16:27 ` Andrei Borzenkov
0 siblings, 1 reply; 3+ messages in thread
From: Vladimir 'phcoder' Serbinenko @ 2017-04-03 8:59 UTC (permalink / raw)
To: The development of GRUB 2
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On Fri, Mar 31, 2017, 06:43 Andrei Borzenkov <arvidjaar@gmail.com> wrote:
> sblock was local and so considered new variable on every loop
> iteration.
>
> While on it, dynamically allocate buffer to reduce stack usage.
>
Looks good. Did you check all instances sizeof, so we don't have sizeof of
pointer?
Did you check return paths for free'ing on all of them?
>
>
> Closes: 50597
>
> ---
> grub-core/fs/btrfs.c | 18 ++++++++++++------
> 1 file changed, 12 insertions(+), 6 deletions(-)
>
> diff --git a/grub-core/fs/btrfs.c b/grub-core/fs/btrfs.c
> index 9cffa91..99e81f9 100644
> --- a/grub-core/fs/btrfs.c
> +++ b/grub-core/fs/btrfs.c
> @@ -229,24 +229,29 @@ read_sblock (grub_disk_t disk, struct
> grub_btrfs_superblock *sb)
> {
> unsigned i;
> grub_err_t err = GRUB_ERR_NONE;
> + struct grub_btrfs_superblock *sblock;
> +
> + sblock = grub_malloc (sizeof (*sblock));
> + if (sblock == NULL)
> + return grub_errno;
> +
> for (i = 0; i < ARRAY_SIZE (superblock_sectors); i++)
> {
> - struct grub_btrfs_superblock sblock;
> /* Don't try additional superblocks beyond device size. */
> - if (i && (grub_le_to_cpu64 (sblock.this_device.size)
> + if (i && (grub_le_to_cpu64 (sblock->this_device.size)
> >> GRUB_DISK_SECTOR_BITS) <= superblock_sectors[i])
> break;
> err = grub_disk_read (disk, superblock_sectors[i], 0,
> - sizeof (sblock), &sblock);
> + sizeof (*sblock), sblock);
> if (err == GRUB_ERR_OUT_OF_RANGE)
> break;
>
> - if (grub_memcmp ((char *) sblock.signature, GRUB_BTRFS_SIGNATURE,
> + if (grub_memcmp ((char *) sblock->signature, GRUB_BTRFS_SIGNATURE,
> sizeof (GRUB_BTRFS_SIGNATURE) - 1) != 0)
> break;
> - if (i == 0 || grub_le_to_cpu64 (sblock.generation)
> + if (i == 0 || grub_le_to_cpu64 (sblock->generation)
> > grub_le_to_cpu64 (sb->generation))
> - grub_memcpy (sb, &sblock, sizeof (sblock));
> + grub_memcpy (sb, sblock, sizeof (*sblock));
> }
>
> if ((err == GRUB_ERR_OUT_OF_RANGE || !err) && i == 0)
> @@ -255,6 +260,7 @@ read_sblock (grub_disk_t disk, struct
> grub_btrfs_superblock *sb)
> if (err == GRUB_ERR_OUT_OF_RANGE)
> grub_errno = err = GRUB_ERR_NONE;
>
> + grub_free (sblock);
> return err;
> }
>
> --
> tg: (8014b7b..) bug/50597 (depends on: master)
>
> _______________________________________________
> Grub-devel mailing list
> Grub-devel@gnu.org
> https://lists.gnu.org/mailman/listinfo/grub-devel
>
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] btrfs: avoid "used uninitialized" error with GCC7
2017-04-03 8:59 ` Vladimir 'phcoder' Serbinenko
@ 2017-04-04 16:27 ` Andrei Borzenkov
0 siblings, 0 replies; 3+ messages in thread
From: Andrei Borzenkov @ 2017-04-04 16:27 UTC (permalink / raw)
To: grub-devel
03.04.2017 11:59, Vladimir 'phcoder' Serbinenko пишет:
> On Fri, Mar 31, 2017, 06:43 Andrei Borzenkov <arvidjaar@gmail.com> wrote:
>
>> sblock was local and so considered new variable on every loop
>> iteration.
>>
>> While on it, dynamically allocate buffer to reduce stack usage.
>>
> Looks good. Did you check all instances sizeof, so we don't have sizeof of
> pointer?
> Did you check return paths for free'ing on all of them?
>
There is one common return path, but I committed light version that just
moves variable out of loop; will commit full version after release.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2017-03-31 16:42 [PATCH] btrfs: avoid "used uninitialized" error with GCC7 Andrei Borzenkov
2017-04-03 8:59 ` Vladimir 'phcoder' Serbinenko
2017-04-04 16:27 ` Andrei Borzenkov
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