show-branch: store resolved head in heap buffer
We resolve HEAD and copy the result to a fixed-size buffer with memcpy, never checking that it actually fits. This bug dates back to 8098a178b (Add git-symbolic-ref, 2005-09-30). Before that we used readlink(), which took a maximum buffer size. We can fix this by using resolve_refdup(), which duplicates the buffer on the heap. That also lets us just check for a NULL pointer to see if we have resolved HEAD, and drop the extra head_p variable. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Jeff King committed
Feb 14, 2017 at 12:27 UTC
d9e557a320bd4695bccad873e176562489b2d199
1 file changed
+5
-14
builtin/show-branch.c
+5
-14
@@ -473,8 +473,7 @@ static void snarf_refs(int head, int remotes)
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static int rev_is_head(char *head, char *name,
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unsigned char *head_sha1, unsigned char *sha1)
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{
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- if ((!head[0]) ||
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- (head_sha1 && sha1 && hashcmp(head_sha1, sha1)))
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+ if (!head || (head_sha1 && sha1 && hashcmp(head_sha1, sha1)))
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return 0;
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if (starts_with(head, "refs/heads/"))
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head += 11;
@@ -621,8 +620,7 @@ int cmd_show_branch(int ac, const char **av, const char *prefix)
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int all_heads = 0, all_remotes = 0;
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int all_mask, all_revs;
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enum rev_sort_order sort_order = REV_SORT_IN_GRAPH_ORDER;
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- char head[128];
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- const char *head_p;
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+ char *head;
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struct object_id head_oid;
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int merge_base = 0;
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int independent = 0;
@@ -786,17 +784,10 @@ int cmd_show_branch(int ac, const char **av, const char *prefix)
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snarf_refs(all_heads, all_remotes);
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}
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- head_p = resolve_ref_unsafe("HEAD", RESOLVE_REF_READING,
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- head_oid.hash, NULL);
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- if (head_p) {
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- size_t head_len = strlen(head_p);
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- memcpy(head, head_p, head_len + 1);
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- }
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- else {
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- head[0] = 0;
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- }
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+ head = resolve_refdup("HEAD", RESOLVE_REF_READING,
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+ head_oid.hash, NULL);
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- if (with_current_branch && head_p) {
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+ if (with_current_branch && head) {
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int has_head = 0;
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for (i = 0; !has_head && i < ref_name_cnt; i++) {
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/* We are only interested in adding the branch