![Fabrice Fontaine](/assets/img/avatar_default.png)
In Pure-FTPd 1.0.49, a stack exhaustion issue was discovered in the listdir function in ls.c. Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com> Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
71 lines
2.5 KiB
Diff
71 lines
2.5 KiB
Diff
From aea56f4bcb9948d456f3fae4d044fd3fa2e19706 Mon Sep 17 00:00:00 2001
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From: Frank Denis <github@pureftpd.org>
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Date: Mon, 30 Dec 2019 17:40:04 +0100
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Subject: [PATCH] listdir(): reuse a single buffer to store every file name to
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display
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Allocating a new buffer for each entry is useless.
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And as these buffers are allocated on the stack, on systems with a
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small stack size, with many entries, the limit can easily be reached,
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causing a stack exhaustion and aborting the user session.
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Reported by Antonio Morales from the GitHub Security Lab team, thanks!
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[Retrieved from:
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https://github.com/jedisct1/pure-ftpd/commit/aea56f4bcb9948d456f3fae4d044fd3fa2e19706]
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Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
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---
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src/ls.c | 15 ++++++++-------
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1 file changed, 8 insertions(+), 7 deletions(-)
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diff --git a/src/ls.c b/src/ls.c
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index cf804c7..f8a588f 100644
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--- a/src/ls.c
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+++ b/src/ls.c
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@@ -661,6 +661,8 @@ static void listdir(unsigned int depth, int f, void * const tls_fd,
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char *names;
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PureFileInfo *s;
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PureFileInfo *r;
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+ char *alloca_subdir;
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+ size_t sizeof_subdir;
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int d;
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if (depth >= max_ls_depth || matches >= max_ls_files) {
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@@ -690,14 +692,12 @@ static void listdir(unsigned int depth, int f, void * const tls_fd,
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}
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outputfiles(f, tls_fd);
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r = dir;
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+ sizeof_subdir = PATH_MAX + 1U;
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+ if ((alloca_subdir = ALLOCA(sizeof_subdir)) == NULL) {
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+ goto toomany;
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+ }
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while (opt_R && r != s) {
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if (r->name_offset != (size_t) -1 && !chdir(FI_NAME(r))) {
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- char *alloca_subdir;
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- const size_t sizeof_subdir = PATH_MAX + 1U;
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-
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- if ((alloca_subdir = ALLOCA(sizeof_subdir)) == NULL) {
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- goto toomany;
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- }
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if (SNCHECK(snprintf(alloca_subdir, sizeof_subdir, "%s/%s",
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name, FI_NAME(r)), sizeof_subdir)) {
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goto nolist;
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@@ -706,8 +706,8 @@ static void listdir(unsigned int depth, int f, void * const tls_fd,
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wrstr(f, tls_fd, alloca_subdir);
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wrstr(f, tls_fd, ":\r\n\r\n");
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listdir(depth + 1U, f, tls_fd, alloca_subdir);
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+
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nolist:
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- ALLOCA_FREE(alloca_subdir);
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if (matches >= max_ls_files) {
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goto toomany;
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}
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@@ -720,6 +720,7 @@ static void listdir(unsigned int depth, int f, void * const tls_fd,
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r++;
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}
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toomany:
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+ ALLOCA_FREE(alloca_subdir);
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free(names);
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free(dir);
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names = NULL;
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