From: Eric Sandeen <sandeen@sandeen.net>
To: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: linux-xfs@vger.kernel.org
Subject: Re: [PATCH 06/10] misc: fix strncpy length complaints
Date: Mon, 22 Apr 2019 16:04:59 -0500 [thread overview]
Message-ID: <0017a715-9a0e-f606-0e88-6226db06920d@sandeen.net> (raw)
In-Reply-To: <20190422205703.GC4676@magnolia>
On 4/22/19 3:57 PM, Darrick J. Wong wrote:
> On Mon, Apr 22, 2019 at 03:48:03PM -0500, Eric Sandeen wrote:
>> On 4/22/19 10:45 AM, Darrick J. Wong wrote:
>>> From: Darrick J. Wong <darrick.wong@oracle.com>
>>>
>>> Fix a number of complaints about feeding sizeof(dest) directly to
>>> strncpy. We do this by declaring the char arrays to be one larger
>>> than necessary and subtracting one, to ensure that we never overfill
>>> the buffer.
>>>
>>> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
>>
>> Hm, you don't actually do what the changelog says, do you? No buffer
>> changes size in this patch.
>
> I'll change it to:
>
> "Fix a number of complaints about feeding sizeof(dest) directly to
> strncpy. We do this by feeding strncpy the length of the buffer minus
> one, having checked that the allocated space are long enough."
sounds good, I'll just fix that here.
>> And FWIW, neither of these was actually a real problem (fgets guarantees
>> a null in the string) but hey, whatever makes gcc happy I guess?
>>
>> (I think we lose a char in the quota array, but 511 chars ought to be
>> enough for anybody right?)
>
> Well... the quota one is reading lines straight out of a file, right?
> So that probably ought to be char buf[PATH_MAX + length of other junk in
> the line], though with the current lower limit now nobody's complained
> so maybe it's fine....
>
> --D
>
>> Patch seems fine, though.
>>
>>> ---
>>> mkfs/xfs_mkfs.c | 13 +++++++++++--
>>> quota/edit.c | 9 ++++++---
>>> 2 files changed, 17 insertions(+), 5 deletions(-)
>>>
>>>
>>> diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c
>>> index 3e2ef92d..db3ad38e 100644
>>> --- a/mkfs/xfs_mkfs.c
>>> +++ b/mkfs/xfs_mkfs.c
>>> @@ -3270,8 +3270,17 @@ finish_superblock_setup(
>>> struct xfs_mount *mp,
>>> struct xfs_sb *sbp)
>>> {
>>> - if (cfg->label)
>>> - strncpy(sbp->sb_fname, cfg->label, sizeof(sbp->sb_fname));
>>> + if (cfg->label) {
>>> + size_t label_len;
>>> +
>>> + /*
>>> + * Labels are null terminated unless the string fits exactly
>>> + * in the label field, so assume sb_fname is zeroed and then
>>> + * do a memcpy because the destination isn't a normal C string.
>>> + */
>>> + label_len = min(sizeof(sbp->sb_fname), strlen(cfg->label));
>>> + memcpy(sbp->sb_fname, cfg->label, label_len);
>>> + }
>>>
>>> sbp->sb_dblocks = cfg->dblocks;
>>> sbp->sb_rblocks = cfg->rtblocks;
>>> diff --git a/quota/edit.c b/quota/edit.c
>>> index b10a5b34..f9938b8a 100644
>>> --- a/quota/edit.c
>>> +++ b/quota/edit.c
>>> @@ -368,8 +368,7 @@ restore_file(
>>> uint type)
>>> {
>>> char buffer[512];
>>> - char devbuffer[512];
>>> - char *dev = NULL;
>>> + char dev[512];
>>> uint mask;
>>> int cnt;
>>> uint32_t id;
>>> @@ -377,7 +376,11 @@ restore_file(
>>>
>>> while (fgets(buffer, sizeof(buffer), fp) != NULL) {
>>> if (strncmp("fs = ", buffer, 5) == 0) {
>>> - dev = strncpy(devbuffer, buffer+5, sizeof(devbuffer));
>>> + /*
>>> + * Copy the device name to dev, strip off the trailing
>>> + * newline, and move on to the next line.
>>> + */
>>> + strncpy(dev, buffer + 5, sizeof(dev) - 1);
>>> dev[strlen(dev) - 1] = '\0';
>>> continue;
>>> }
>>>
>
next prev parent reply other threads:[~2019-04-22 21:05 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-22 15:44 [PATCH v3 00/10] xfsprogs-5.0: fix various problems Darrick J. Wong
2019-04-22 15:44 ` [PATCH 01/10] scrub: fix Makefile targets which depend on builddefs Darrick J. Wong
2019-04-22 18:27 ` Eric Sandeen
2019-04-22 18:28 ` Bill O'Donnell
2019-04-22 15:45 ` [PATCH 02/10] xfs_info: use findmnt to handle mounted block devices Darrick J. Wong
2019-04-22 18:35 ` Eric Sandeen
2019-04-22 19:27 ` Bill O'Donnell
2019-04-22 15:45 ` [PATCH 03/10] xfs_repair: correctly account for free space btree shrinks when fixing freelist Darrick J. Wong
2019-04-22 19:24 ` Eric Sandeen
2019-04-22 19:36 ` Bill O'Donnell
2019-04-22 15:45 ` [PATCH 04/10] libxfs: retain ifork_ops when flushing inode Darrick J. Wong
2019-04-22 19:40 ` Bill O'Donnell
2019-04-22 19:45 ` Eric Sandeen
2019-10-02 6:00 ` Arkadiusz Miśkiewicz
2019-04-22 15:45 ` [PATCH 05/10] libxfs: drop the ifork_ops parameter from _inode_verify_forks Darrick J. Wong
2019-04-22 19:43 ` Bill O'Donnell
2019-04-22 20:49 ` Eric Sandeen
2019-04-22 15:45 ` [PATCH 06/10] misc: fix strncpy length complaints Darrick J. Wong
2019-04-22 20:48 ` Eric Sandeen
2019-04-22 20:57 ` Darrick J. Wong
2019-04-22 21:04 ` Eric Sandeen [this message]
2019-04-22 21:07 ` Eric Sandeen
2019-04-23 15:07 ` Bill O'Donnell
2019-04-22 15:45 ` [PATCH 07/10] libxfs: refactor buffer item release code Darrick J. Wong
2019-04-22 21:26 ` Eric Sandeen
2019-04-22 21:35 ` Darrick J. Wong
2019-04-22 21:40 ` Eric Sandeen
2019-04-23 20:51 ` [PATCH v2 " Darrick J. Wong
2019-04-23 20:56 ` Bill O'Donnell
2019-04-22 15:45 ` [PATCH 08/10] libxfs: don't touch buffer log item pointer when flushing inode log item Darrick J. Wong
2019-04-23 17:56 ` Eric Sandeen
2019-04-23 20:52 ` Bill O'Donnell
2019-04-22 15:45 ` [PATCH 09/10] libxfs: fix buffer log item lifetime weirdness Darrick J. Wong
2019-04-23 21:15 ` Bill O'Donnell
2019-04-22 15:45 ` [PATCH 10/10] libxfs: shorten inode item lifetime Darrick J. Wong
2019-04-23 21:22 ` Bill O'Donnell
2019-04-23 21:04 ` [PATCH 11/10] libfrog: fix memory leak in bitmap_free Darrick J. Wong
2019-04-23 21:23 ` Bill O'Donnell
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