From: Peter Marko <[email protected]> Pick patch which fixes this CVE as discussed in [1].
[1] https://lists.busybox.net/pipermail/busybox/2026-July/092392.html Signed-off-by: Peter Marko <[email protected]> --- .../busybox/busybox/CVE-2026-38754.patch | 155 ++++++++++++++++++ meta/recipes-core/busybox/busybox_1.36.1.bb | 1 + 2 files changed, 156 insertions(+) create mode 100644 meta/recipes-core/busybox/busybox/CVE-2026-38754.patch diff --git a/meta/recipes-core/busybox/busybox/CVE-2026-38754.patch b/meta/recipes-core/busybox/busybox/CVE-2026-38754.patch new file mode 100644 index 00000000000..d263d72d9f3 --- /dev/null +++ b/meta/recipes-core/busybox/busybox/CVE-2026-38754.patch @@ -0,0 +1,155 @@ +From a448b6d5b21e5b21249391389b6f0551d9bea136 Mon Sep 17 00:00:00 2001 +From: Sanghyun Park <[email protected]> +Date: Thu, 18 Jun 2026 17:04:20 +0900 +Subject: [PATCH] ash: fix out-of-bounds read in ifsbreakup() + +ifsfree() does not only release allocated ifsregion nodes; it also clears +the global IFS region state used by ifsbreakup(). If argstr() raises an +error while expanding an argument, ash longjmps out of expandarg() before +that cleanup runs, leaving stale IFS split offsets behind. + +A later expansion can reuse the stack for a shorter string. ifsbreakup() +then sees the stale IFS state, trusts the old offsets, and can walk past +the current stack block before dereferencing p. + +Follow dash's root-cause fix: when an expansion-related handler catches +EXERROR and continues, restore the handler and call ifsfree(). Apply +the cleanup to redirectsafe(), expandstr(), and evaltree(). + +Upstream commit: + + Date: Mon Dec 5 23:02:01 2022 +0800 + expand: Add ifsfree to expand to fix a logic error that causes a buffer over-read + + On Mon, Jun 20, 2022 at 02:27:10PM -0400, Alex Gorinson wrote: + > Due to a logic error in the ifsbreakup function in expand.c if a + > heredoc and normal command is run one after the other by means of a + > semi-colon, when the second command drops into ifsbreakup the command + > will be evaluated with the ifslastp/ifsfirst struct that was set when + > the here doc was evaluated. This results in a buffer over-read that + > can leak the program's heap, stack, and arena addresses which can be + > used to beat ASLR. + > + > Steps to Reproduce: + > First bug: + > cmd args: ~/exampleDir/example> dash + > $ M='AAAAAAAAAAAAAAAAA' <note: 17 A's> + > $ q00(){ + > $ <<000;echo + > $ ${D?$M$M$M$M$M$M} <note: 6 $M's> + > $ 000 + > $ } + > $ q00 <note: After the q00 is typed in, the leak + > should be echo'd out; this works with ash, busybox ash, and dash and + > with all option args.> + > + > Patch: + > Adding the following to expand.c will fix both bugs in one go. + > (Thank you to Harald van Dijk and Michael Greenberg for doing the + > heavy lifting for this patch!) + > ========================== + > --- a/src/expand.c + > +++ b/src/expand.c + > @@ -859,6 +859,7 @@ + > if (discard) + > return -1; + > + > +ifsfree(); + > sh_error("Bad substitution"); + > } + > + > @@ -1739,6 +1740,7 @@ + > } else + > msg = umsg; + > } + > +ifsfree(); + > sh_error("%.*s: %s%s", end - var - 1, var, msg, tail); + > } + > ========================== + + Thanks for the report! + + I think it's better to add the ifsfree() call to the exception + handling path as other sh_error calls may trigger this too. + +function old new delta +restore_handler_expandarg - 33 +33 +evaltree 725 711 -14 +static.redirectsafe 141 124 -17 +expandstr 262 242 -20 +------------------------------------------------------------------------------ +(add/remove: 1/0 grow/shrink: 0/3 up/down: 36/-45) Total: -18 bytes + +Signed-off-by: Sanghyun Park <[email protected]> +Signed-off-by: Denys Vlasenko <[email protected]> + +CVE: CVE-2026-38754 +Upstream-Status: Backport [https://github.com/vda-linux/busybox_mirror/commit/a448b6d5b21e5b21249391389b6f0551d9bea136] +Signed-off-by: Peter Marko <[email protected]> +--- + shell/ash.c | 24 +++++++++++++++--------- + 1 file changed, 15 insertions(+), 9 deletions(-) + +diff --git a/shell/ash.c b/shell/ash.c +index fb887f31b..b8ff67b16 100644 +--- a/shell/ash.c ++++ b/shell/ash.c +@@ -5480,6 +5480,7 @@ stoppedjobs(void) + */ + /* openhere needs this forward reference */ + static void expandhere(union node *arg); ++static void ifsfree(void); + static int + openhere(union node *redir) + { +@@ -5909,6 +5910,17 @@ redirect(union node *redir, int flags) + // preverrout_fd = copied_fd2; + } + ++static void ++restore_handler_expandarg(struct jmploc *savehandler, int err) ++{ ++ exception_handler = savehandler; ++ if (err) { ++ if (exception_type != EXERROR) ++ longjmp(exception_handler->loc, 1); ++ ifsfree(); ++ } ++} ++ + static int + redirectsafe(union node *redir, int flags) + { +@@ -5924,9 +5936,7 @@ redirectsafe(union node *redir, int flags) + exception_handler = &jmploc; + redirect(redir, flags); + } +- exception_handler = savehandler; +- if (err && exception_type != EXERROR) +- longjmp(exception_handler->loc, 1); ++ restore_handler_expandarg(savehandler, err); + RESTORE_INT(saveint); + return err; + } +@@ -9435,9 +9445,7 @@ evaltree(union node *n, int flags) + trap_depth--; + in_trap_ERR = 0; + +- exception_handler = savehandler; +- if (err && exception_type != EXERROR) +- longjmp(exception_handler->loc, 1); ++ restore_handler_expandarg(savehandler, err); + + exitstatus = savestatus; + } +@@ -13444,9 +13452,7 @@ expandstr(const char *ps, int syntax_type) + result = stackblock(); + + out: +- exception_handler = savehandler; +- if (err && exception_type != EXERROR) +- longjmp(exception_handler->loc, 1); ++ restore_handler_expandarg(savehandler, err); + + doprompt = saveprompt; + /* Try: PS1='`xxx(`' */ diff --git a/meta/recipes-core/busybox/busybox_1.36.1.bb b/meta/recipes-core/busybox/busybox_1.36.1.bb index 7929d396c85..60796de9ce2 100644 --- a/meta/recipes-core/busybox/busybox_1.36.1.bb +++ b/meta/recipes-core/busybox/busybox_1.36.1.bb @@ -66,6 +66,7 @@ SRC_URI = "https://busybox.net/downloads/busybox-${PV}.tar.bz2;name=tarball \ file://CVE-2026-26157-CVE-2026-26158-02.patch \ file://CVE-2026-29004-01.patch \ file://CVE-2026-29004-02.patch \ + file://CVE-2026-38754.patch \ " SRC_URI:append:libc-musl = " file://musl.cfg " # TODO http://lists.busybox.net/pipermail/busybox/2023-January/090078.html
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