From e52ca1bf3a6e3645f3dda0de7b84ee0ae26dc1e1 Mon Sep 17 00:00:00 2001 From: Rik van Riel Date: Tue, 10 Oct 2023 23:30:13 -0400 Subject: [PATCH] execve.2: execve also returns E2BIG if a string is too long The execve syscall returns -E2BIG in 3 cases: - The total length of the command line arguments and environment is too large. - An argument or environment string (including the NUL byte) is longer than MAX_ARG_STRLEN. - The full path to the executable (including the NUL byte) exceeds MAX_ARG_STRLEN. Spell out all 3 cases in the -E2BIG section. Discovered by moving a too large commandline parameter to an environment variable, and finding that things still did not work. Examined the code in fs/exec.c to get the details. This simple shell script starts failing at 2^17 on a system with 4kB page size: ./exec2big.sh: line 10: /bin/true: Argument list too long fork failed at loop 17 STRING="a" for loop in `seq 20`; do STRING="$STRING$STRING" export STRING if /bin/true ; then : # still under the limit else echo "fork failed at loop $loop" fi done Signed-off-by: Rik van Riel Suggested-by: Matthew House --- man2/execve.2 | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/man2/execve.2 b/man2/execve.2 index 0d9582492..b68910177 100644 --- a/man2/execve.2 +++ b/man2/execve.2 @@ -449,7 +449,12 @@ The total number of bytes in the environment .RI ( envp ) and argument list .RI ( argv ) -is too large. +is too large, +an argument or environment string is too long, +or the full +.I pathname +of the executable is too long. +The terminating NUL is counted as part of the string length. .TP .B EACCES Search permission is denied on a component of the path prefix of