From: nabijaczleweli@nabijaczleweli.xyz   
      
   Package: linux-image-6.18.10+deb14-amd64   
   Version: 6.18.10-1   
   Severity: normal   
      
   Dear Maintainer,   
      
   I reproduce this on 6.18.10+deb14-amd64 (current nightly d-i),   
   6.1.0-35-amd64, and 6.7.7-amd64:   
      
   	$ cat a.c   
   	int main() {   
   			close(0);   
   			open("/proc/self/maps", 0);   
   			char    buf[20];   
   			read(0, buf, sizeof(buf));   
   			execlp("cat", "cat", (void *)0);   
   	}   
   	$ cc a.c   
   	$ ./a.out   
   	b3000 r--p 00000000 00:8a 816985                     /home/nabi   
   aczleweli/uwu/otp/a.out   
   	$ sed -e 's:read://&:' -e s/cat/wc/ a.c > b.c   
   	$ cc b.c   
   	$ ./a.out   
   	0 0 0   
      
   You can reproduce this with bash with  wc < /proc/self/maps,   
   which yields 0 0 0 because bash does fork -> open -> exec.   
      
   dash does open -> fork -> exec, and it shows dash's maps.   
      
   Arguably bash is more correct, except Linux doesn't implement the file   
   in a useful way (doesn't implement it correctly(?)).   
      
   For non-/self/ I tried:   
   	1$ echo $$   
   	1727476   
   	1$ exec sleep inf   # after the sleep below   
      
   	2$ (sleep 10; wc) < /proc/1727476/maps   
   	0 0 0   
   and   
   	1$ echo $$   
   	1730151   
   	1$ exec sleep inf   # after the sleep below   
      
   	2$ (head -c 32; sleep 10; wc) < /proc/1730151/maps   
       55cf54298000-55cf542c7000 r--p 01 4 55   
   which replicates this directly.   
      
   (read()ing a /proc/$pid/maps fd after $pid does exist returns ESRCH,   
    which is as-expected I think.)   
      
   Best,   
      
   -- System Information:   
   Debian Release: 12.11   
     APT prefers oldstable-updates   
     APT policy: (500, 'oldstable-updates'), (500, 'oldstable-security'), (500,   
   'oldstable-debug'), (500, 'oldstable')   
   Architecture: amd64 (x86_64)   
   Foreign Architectures: i386   
      
   Kernel: Linux 6.1.0-35-amd64 (SMP w/24 CPU threads; PREEMPT)   
   Kernel taint flags: TAINT_PROPRIETARY_MODULE, TAINT_FIRMWARE_WORKAROUND,   
   TAINT_OOT_MODULE, TAINT_UNSIGNED_MODULE   
   Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8),    
   ANGUAGE=en_GB:en   
   Shell: /bin/sh linked to /usr/bin/dash   
   Init: systemd (via /run/systemd/system)   
   LSM: AppArmor: enabled   
      
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