File fix-CVE-2022-39260.patch of Package git.34091

Overview Repositories Revisions Requests Users Attributes Meta

File fix-CVE-2022-39260.patch of Package git.34091

commit 0ca6ead81edd4fb1984b69aae87c1189e3025530
Author: Kevin Backhouse <kevinbackhouse@github.com>
Date:   Wed Sep 28 18:53:32 2022 -0400

alias.c: reject too-long cmdline strings in split_cmdline()
    
    This function improperly uses an int to represent the number of entries
    in the resulting argument array. This allows a malicious actor to
    intentionally overflow the return value, leading to arbitrary heap
    writes.
    
    Because the resulting argv array is typically passed to execv(), it may
    be possible to leverage this attack to gain remote code execution on a
    victim machine. This was almost certainly the case for certain
    configurations of git-shell until the previous commit limited the size
    of input it would accept. Other calls to split_cmdline() are typically
    limited by the size of argv the OS is willing to hand us, so are
    similarly protected.
    
    So this is not strictly fixing a known vulnerability, but is a hardening
    of the function that is worth doing to protect against possible unknown
    vulnerabilities.
    
    One approach to fixing this would be modifying the signature of
    `split_cmdline()` to look something like:
    
        int split_cmdline(char *cmdline, const char ***argv, size_t *argc);
    
    Where the return value of `split_cmdline()` is negative for errors, and
    zero otherwise. If non-NULL, the `*argc` pointer is modified to contain
    the size of the `**argv` array.
    
    But this implies an absurdly large `argv` array, which more than likely
    larger than the system's argument limit. So even if split_cmdline()
    allowed this, it would fail immediately afterwards when we called
    execv(). So instead of converting all of `split_cmdline()`'s callers to
    work with `size_t` types in this patch, instead pursue the minimal fix
    here to prevent ever returning an array with more than INT_MAX entries
    in it.
    
    Signed-off-by: Kevin Backhouse <kevinbackhouse@github.com>
    Signed-off-by: Taylor Blau <me@ttaylorr.com>
    Signed-off-by: Jeff King <peff@peff.net>
    Signed-off-by: Taylor Blau <me@ttaylorr.com>

diff --git a/alias.c b/alias.c
index c471538020..00abde0817 100644
--- a/alias.c
+++ b/alias.c
@@ -46,14 +46,16 @@ void list_aliases(struct string_list *list)
 
 #define SPLIT_CMDLINE_BAD_ENDING 1
 #define SPLIT_CMDLINE_UNCLOSED_QUOTE 2
+#define SPLIT_CMDLINE_ARGC_OVERFLOW 3
 static const char *split_cmdline_errors[] = {
 	N_("cmdline ends with \\"),
-	N_("unclosed quote")
+	N_("unclosed quote"),
+	N_("too many arguments"),
 };
 
 int split_cmdline(char *cmdline, const char ***argv)
 {
-	int src, dst, count = 0, size = 16;
+	size_t src, dst, count = 0, size = 16;
 	char quoted = 0;
 
 	ALLOC_ARRAY(*argv, size);
@@ -96,6 +98,11 @@ int split_cmdline(char *cmdline, const char ***argv)
 		return -SPLIT_CMDLINE_UNCLOSED_QUOTE;
 	}
 
+	if (count >= INT_MAX) {
+		FREE_AND_NULL(*argv);
+		return -SPLIT_CMDLINE_ARGC_OVERFLOW;
+	}
+
 	ALLOC_GROW(*argv, count + 1, size);
 	(*argv)[count] = NULL;

Places

File fix-CVE-2022-39260.patch of Package git.34091

Places