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From: Adhemerval Zanella <>
Cc: Adrian Ratiu <>
Subject: [PATCH] arm: Remove unused ldr _dl_start_user
Date: Mon,  5 Feb 2024 16:18:08 +0000	[thread overview]
Message-ID: <> (raw)

The commit 49d877a80b29d3002887b084eec6676d9f5fec18 (arm: Remove
_dl_skip_args usage) removed the _SKIP_ARGS literal, which was
previously loader to r4 on loader _start.  However, the cleanup did not
remove the following 'ldr r4, [sl, r4]' on _dl_start_user, used to check
to skip the arguments after ld self-relocations.

In my testing, the kernel initially set r4 to 0, which makes the
ldr instruction just read the _GLOBAL_OFFSET_TABLE_.  However, since r4
is a caller-saved register; a different runtime might not zero
initialize it and thus trigger an invalid memory access.

Checked on arm-linux-gnu.

Reported-by: Adrian Ratiu <>
 sysdeps/arm/dl-machine.h | 1 -
 1 file changed, 1 deletion(-)

diff --git a/sysdeps/arm/dl-machine.h b/sysdeps/arm/dl-machine.h
index b857bbc868..dd1a0f6b6e 100644
--- a/sysdeps/arm/dl-machine.h
+++ b/sysdeps/arm/dl-machine.h
@@ -139,7 +139,6 @@ _start:\n\
 	adr	r6, .L_GET_GOT\n\
 	add	sl, sl, r6\n\
-	ldr	r4, [sl, r4]\n\
 	@ save the entry point in another register\n\
 	mov	r6, r0\n\
 	@ get the original arg count\n\

             reply	other threads:[~2024-02-05 16:18 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-02-05 16:18 Adhemerval Zanella [this message]
2024-02-05 17:06 ` Szabolcs Nagy
2024-02-05 17:08   ` Adhemerval Zanella Netto
2024-02-05 17:13 ` Sam James
2024-02-05 18:09   ` Adhemerval Zanella Netto
2024-02-05 18:19     ` Sam James

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