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main: fix invalid access when filtering xattrs

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Fix an invalid access when filtering internal xattrs.

The size passed to memmove was longer than the remaining bytes to
process.

As part of the fix: move the filtering logic to a separate function.

Closes: https://github.com/containers/fuse-overlayfs/issues/293

Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>
This commit is contained in:
Giuseppe Scrivano 2021-06-21 15:09:43 +02:00
parent 0087bbc85f
commit bf381d3afb
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GPG Key ID: E4730F97F60286ED
1 changed files with 27 additions and 16 deletions
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43
main.c
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@ -2474,6 +2474,32 @@ ovl_releasedir (fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi)
fuse_reply_err (req, 0);
}
/* in-place filter xattrs that cannot be accessed. */
static ssize_t
filter_xattrs_list (char *buf, ssize_t len)
{
size_t i;
ssize_t ret = len;
for (i = 0; buf && i < ret;)
{
size_t current_len;
const char *cur_attr = buf + i;
ssize_t remaining = len - i;
current_len = strlen (cur_attr) + 1;
if (can_access_xattr (cur_attr))
i += current_len;
else
{
memmove (buf + i, cur_attr + current_len, remaining - current_len);
ret -= current_len;
}
}
return len;
}
static void
ovl_listxattr (fuse_req_t req, fuse_ino_t ino, size_t size)
{
@ -2525,22 +2551,7 @@ ovl_listxattr (fuse_req_t req, fuse_ino_t ino, size_t size)
return;
}
len = ret;
for (i = 0; buf && i < len;)
{
size_t current_len;
const char *cur_attr = buf + i;
current_len = strlen (cur_attr) + 1;
if (can_access_xattr (cur_attr))
i += current_len;
else
{
memmove (buf + i, cur_attr + current_len, len - current_len);
len -= current_len;
}
}
len = filter_xattrs_list (buf, ret);
if (size == 0)
fuse_reply_xattr (req, len);