From: Ashishkumar Parmar <[email protected]> Pick the upstream backport [1] for CVE-2026-43620 as mentioned in [2], where a malicious rsync server could trigger an out-of-bounds file-list access in the receiver.
[1] https://github.com/RsyncProject/rsync/commit/0a5fa00fdcbacbebb89daca0ae68ae320f22dc74 [2] https://www.cve.org/CVERecord?id=CVE-2026-43620 Signed-off-by: Ashishkumar Parmar <[email protected]> --- .../rsync/files/CVE-2026-43620.patch | 124 ++++++++++++++++++ meta/recipes-devtools/rsync/rsync_3.2.7.bb | 1 + 2 files changed, 125 insertions(+) create mode 100644 meta/recipes-devtools/rsync/files/CVE-2026-43620.patch diff --git a/meta/recipes-devtools/rsync/files/CVE-2026-43620.patch b/meta/recipes-devtools/rsync/files/CVE-2026-43620.patch new file mode 100644 index 0000000000..dd50f1ebd6 --- /dev/null +++ b/meta/recipes-devtools/rsync/files/CVE-2026-43620.patch @@ -0,0 +1,124 @@ +From 6495fc027ad48678c98eab3de4224e29473ccb08 Mon Sep 17 00:00:00 2001 +From: Andrew Tridgell <[email protected]> +Date: Tue, 5 May 2026 16:48:16 +1000 +Subject: [PATCH] receiver: add parent_ndx<0 guard, mirroring 797e17f + +Commit 797e17f ("fixed an invalid access to files array") added a +parent_ndx < 0 guard to send_files() in sender.c, but the visually- +identical block in recv_files() in receiver.c was not updated. A +malicious rsync:// server can therefore drive any connecting client +into the same out-of-bounds dir_flist->files[-1] read followed by a +file_struct dereference in f_name() one line later. + +Reach: protocol-30+ default (inc_recurse) makes flist.c:2745 set +parent_ndx = -1 on the first received flist when the sender omits a +leading "." entry; rsync.c flist_for_ndx() does not reject ndx == 0 +in that state because the range check evaluates 0 < 0 = false; and +read_ndx_and_attrs() only validates ndx with the ITEM_TRANSFER bit +set, so iflags=ITEM_IS_NEW (or any other non-transfer iflag word) +bypasses the check. + +Apply the same guard receiver-side. Confirmed: the same PoC (a +minimal Python rsyncd that handshakes with CF_INC_RECURSE, sends a +no-leading-"." flist, and emits ndx=0 with ITEM_IS_NEW) crashes +unpatched 3.4.2 with SEGV_MAPERR si_addr=0x4101a-class in the +receiver child; with this guard it exits cleanly with code 2 +(RERR_PROTOCOL). + +The attack surface delta over the sender variant is large: +the original was malicious-client -> daemon, this is +malicious-server -> any rsync client doing a normal rsync:// +or remote-shell pull. + +Reported by Pratham Gupta (alchemy1729). + +Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]> + +CVE: CVE-2026-43620 +Upstream-Status: Backport [https://github.com/RsyncProject/rsync/commit/0a5fa00fdcbacbebb89daca0ae68ae320f22dc74] + +(cherry picked from commit 0a5fa00fdcbacbebb89daca0ae68ae320f22dc74) +Signed-off-by: Ashishkumar Parmar <[email protected]> +--- + generator.c | 4 ++++ + io.c | 3 +++ + receiver.c | 7 ++++++- + sender.c | 2 ++ + 4 files changed, 15 insertions(+), 1 deletion(-) + +diff --git a/generator.c b/generator.c +index b80eb2e3..38f5ad33 100644 +--- a/generator.c ++++ b/generator.c +@@ -2146,6 +2146,8 @@ void check_for_finished_files(int itemizing, enum logcode code, int check_redo) + if (send_failed) + ndx = get_hlink_num(); + flist = flist_for_ndx(ndx, "check_for_finished_files.1"); ++ if (ndx < flist->ndx_start) ++ exit_cleanup(RERR_PROTOCOL); + file = flist->files[ndx - flist->ndx_start]; + assert(file->flags & FLAG_HLINKED); + if (send_failed) +@@ -2174,6 +2176,8 @@ void check_for_finished_files(int itemizing, enum logcode code, int check_redo) + + flist = cur_flist; + cur_flist = flist_for_ndx(ndx, "check_for_finished_files.2"); ++ if (ndx < cur_flist->ndx_start) ++ exit_cleanup(RERR_PROTOCOL); + + file = cur_flist->files[ndx - cur_flist->ndx_start]; + if (solo_file) +diff --git a/io.c b/io.c +index bb60eeca..c654a7ba 100644 +--- a/io.c ++++ b/io.c +@@ -1090,6 +1090,9 @@ static void got_flist_entry_status(enum festatus status, int ndx) + { + struct file_list *flist = flist_for_ndx(ndx, "got_flist_entry_status"); + ++ if (ndx < flist->ndx_start) ++ exit_cleanup(RERR_PROTOCOL); ++ + if (remove_source_files) { + active_filecnt--; + active_bytecnt -= F_LENGTH(flist->files[ndx - flist->ndx_start]); +diff --git a/receiver.c b/receiver.c +index 63e5cedb..0a993e0f 100644 +--- a/receiver.c ++++ b/receiver.c +@@ -467,7 +467,10 @@ static void handle_delayed_updates(char *local_name) + static void no_batched_update(int ndx, BOOL is_redo) + { + struct file_list *flist = flist_for_ndx(ndx, "no_batched_update"); +- struct file_struct *file = flist->files[ndx - flist->ndx_start]; ++ struct file_struct *file; ++ if (ndx < flist->ndx_start) ++ exit_cleanup(RERR_PROTOCOL); ++ file = flist->files[ndx - flist->ndx_start]; + + rprintf(FERROR_XFER, "(No batched update for%s \"%s\")\n", + is_redo ? " resend of" : "", f_name(file, NULL)); +@@ -604,6 +607,8 @@ int recv_files(int f_in, int f_out, char *local_name) + + if (ndx - cur_flist->ndx_start >= 0) + file = cur_flist->files[ndx - cur_flist->ndx_start]; ++ else if (cur_flist->parent_ndx < 0) ++ exit_cleanup(RERR_PROTOCOL); + else + file = dir_flist->files[cur_flist->parent_ndx]; + fname = local_name ? local_name : f_name(file, fbuf); +diff --git a/sender.c b/sender.c +index 99f431fe..033f87e5 100644 +--- a/sender.c ++++ b/sender.c +@@ -140,6 +140,8 @@ void successful_send(int ndx) + return; + + flist = flist_for_ndx(ndx, "successful_send"); ++ if (ndx < flist->ndx_start) ++ exit_cleanup(RERR_PROTOCOL); + file = flist->files[ndx - flist->ndx_start]; + if (!change_pathname(file, NULL, 0)) + return; +-- +2.35.6 diff --git a/meta/recipes-devtools/rsync/rsync_3.2.7.bb b/meta/recipes-devtools/rsync/rsync_3.2.7.bb index e232abafc3..b1483fc6a6 100644 --- a/meta/recipes-devtools/rsync/rsync_3.2.7.bb +++ b/meta/recipes-devtools/rsync/rsync_3.2.7.bb @@ -39,6 +39,7 @@ SRC_URI = "https://download.samba.org/pub/${BPN}/src/${BP}.tar.gz \ file://CVE-2026-43619_p3.patch \ file://CVE-2026-43619_p4.patch \ file://CVE-2026-43618.patch \ + file://CVE-2026-43620.patch \ " SRC_URI[sha256sum] = "4e7d9d3f6ed10878c58c5fb724a67dacf4b6aac7340b13e488fb2dc41346f2bb" -- 2.44.1
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