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patch 9.1.0162: problem with writing extended attributes on failure

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Problem:  problem with writing extended attributes on failure
Solution: Change return type to ssize_t and check listxattr's return
          value correctly on failure (Paul Tagliamonte)

The existing logic will return when the listxattr call returns with the
errno set to ENOTSUP (or a size of 0 bytes), without checking to see if
listxattr actually failed. listxattr can fail with at least E2BIG,
ENOTSUP, ERANGE, or anything that `stat(2)` can fail with (in my case;
ENOENT from stat).

The returned size is stored to a size_t, but the return type is a
ssize_t. On failure, listxattr returns -1, which will get translated to
size_t's MAX. If the listxattr call failed with anything other than
ENOTSUP, this triggers a request for size_t MAX bytes.

This means that, if the listxattr call fails with anything other than
ENOTSUP on save, vim will error with

`E342: Out of memory!  (allocating 18446744073709551615 bytes)`

(keen observers will note 18446744073709551615 is 0xffffffffffffffff)

In reality, this is likely masking a different (usually filesystem?)
error -- but at least it's an error being pushed to the user now, and we
don't try to allocate size_t MAX bytes.

I've opted to change the type that we store listxattr to from size_t to
ssize_t, to match listxattr(2)'s signature, and to check for the -1
return value. Additionally, I've removed the errno check -- if we get a
listxattr failure for any reason, we may as well bail without trying;
it's not like we can even recover.

closes: #14169

Signed-off-by: Paul Tagliamonte <paultag@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
This commit is contained in:
Paul R. Tagliamonte 2024-03-10 08:35:10 +01:00 committed by Christian Brabandt
parent ca0e0d2708
commit 14759ded57
No known key found for this signature in database
GPG Key ID: F3F92DA383FDDE09
2 changed files with 6 additions and 4 deletions
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8
src/os_unix.c
View File

@ -3048,7 +3048,7 @@ mch_copy_sec(char_u *from_file, char_u *to_file)
size = listxattr((char *)from_file, NULL, 0); size = listxattr((char *)from_file, NULL, 0);
// not supported or no attributes to copy // not supported or no attributes to copy
if (errno == ENOTSUP || size == 0) if (size <= 0)
return; return;
for (index = 0 ; index < (int)(sizeof(smack_copied_attributes) for (index = 0 ; index < (int)(sizeof(smack_copied_attributes)
@ -3112,8 +3112,8 @@ mch_copy_sec(char_u *from_file, char_u *to_file)
mch_copy_xattr(char_u *from_file, char_u *to_file) mch_copy_xattr(char_u *from_file, char_u *to_file)
{ {
char *xattr_buf; char *xattr_buf;
size_t size; ssize_t size;
size_t tsize; ssize_t tsize;
ssize_t keylen, vallen, max_vallen = 0; ssize_t keylen, vallen, max_vallen = 0;
char *key; char *key;
char *val = NULL; char *val = NULL;
@ -3125,7 +3125,7 @@ mch_copy_xattr(char_u *from_file, char_u *to_file)
// get the length of the extended attributes // get the length of the extended attributes
size = listxattr((char *)from_file, NULL, 0); size = listxattr((char *)from_file, NULL, 0);
// not supported or no attributes to copy // not supported or no attributes to copy
if (errno == ENOTSUP || size == 0) if (size <= 0)
return; return;
xattr_buf = (char*)alloc(size); xattr_buf = (char*)alloc(size);
if (xattr_buf == NULL) if (xattr_buf == NULL)

2
src/version.c
View File

@ -704,6 +704,8 @@ static char *(features[]) =
static int included_patches[] = static int included_patches[] =
{ /* Add new patch number below this line */ { /* Add new patch number below this line */
/**/
162,
/**/ /**/
161, 161,
/**/ /**/