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attr.c: move ATTR_MAX_FILE_SIZE check into read_attr_from_buf()

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Commit 3c50032ff5 (attr: ignore overly large gitattributes files,
2022-12-01) added a defense-in-depth check to ensure that .gitattributes
blobs read from the index do not exceed ATTR_MAX_FILE_SIZE (100 MB).

But there were two cases added shortly after 3c50032ff5 was written
which do not apply similar protections:

  - 47cfc9bd7d (attr: add flag `--source` to work with tree-ish,
    2023-01-14)

  - 4723ae1007 (attr.c: read attributes in a sparse directory,
    2023-08-11) added a similar

Ensure that we refuse to process a .gitattributes blob exceeding
ATTR_MAX_FILE_SIZE when reading from either an arbitrary tree object or
a sparse directory. This is done by pushing the ATTR_MAX_FILE_SIZE check
down into the low-level `read_attr_from_buf()`.

In doing so, plug a leak in `read_attr_from_index()` where we would
accidentally leak the large buffer upon detecting it is too large to
process.

(Since `read_attr_from_buf()` handles a NULL buffer input, we can remove
a NULL check before calling it in `read_attr_from_index()` as well).

Co-authored-by: Jeff King <peff@peff.net>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Taylor Blau
2024-05-03 15:12:36 -04:00
committed by Junio C Hamano
parent 3c2a3fdc38
commit c793f9cb08
2 changed files with 19 additions and 10 deletions
Download Patch File Download Diff File Expand all files Collapse all files

19
attr.c
View File

@ -765,8 +765,8 @@ static struct attr_stack *read_attr_from_file(const char *path, unsigned flags)
return res;
}
static struct attr_stack *read_attr_from_buf(char *buf, const char *path,
unsigned flags)
static struct attr_stack *read_attr_from_buf(char *buf, size_t length,
const char *path, unsigned flags)
{
struct attr_stack *res;
char *sp;
@ -774,6 +774,11 @@ static struct attr_stack *read_attr_from_buf(char *buf, const char *path,
if (!buf)
return NULL;
if (length >= ATTR_MAX_FILE_SIZE) {
warning(_("ignoring overly large gitattributes blob '%s'"), path);
free(buf);
return NULL;
}
CALLOC_ARRAY(res, 1);
for (sp = buf; *sp;) {
@ -813,7 +818,7 @@ static struct attr_stack *read_attr_from_blob(struct index_state *istate,
return NULL;
}
return read_attr_from_buf(buf, path, flags);
return read_attr_from_buf(buf, sz, path, flags);
}
static struct attr_stack *read_attr_from_index(struct index_state *istate,
@ -860,13 +865,7 @@ static struct attr_stack *read_attr_from_index(struct index_state *istate,
stack = read_attr_from_blob(istate, &istate->cache[sparse_dir_pos]->oid, relative_path, flags);
} else {
buf = read_blob_data_from_index(istate, path, &size);
if (!buf)
return NULL;
if (size >= ATTR_MAX_FILE_SIZE) {
warning(_("ignoring overly large gitattributes blob '%s'"), path);
return NULL;
}
stack = read_attr_from_buf(buf, path, flags);
stack = read_attr_from_buf(buf, size, path, flags);
}
return stack;
}