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authorChristian Krinitsin <mail@krinitsin.com>2025-07-06 16:43:19 +0000
committerChristian Krinitsin <mail@krinitsin.com>2025-07-06 16:43:19 +0000
commit238ec2b7cc1557d6f34c33cc482e4d0cd3e266dd (patch)
treecd8a1b75ba7b3543eb7fe6857f408e7be4d9fd0b /results/classifier/gemma3:27b/syscall/1728116
parent96049c939b1916d80532630d63c14e04d5244f1d (diff)
downloademulator-bug-study-238ec2b7cc1557d6f34c33cc482e4d0cd3e266dd.tar.gz
emulator-bug-study-238ec2b7cc1557d6f34c33cc482e4d0cd3e266dd.zip
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Diffstat (limited to 'results/classifier/gemma3:27b/syscall/1728116')
-rw-r--r--results/classifier/gemma3:27b/syscall/172811650
1 files changed, 50 insertions, 0 deletions
diff --git a/results/classifier/gemma3:27b/syscall/1728116 b/results/classifier/gemma3:27b/syscall/1728116
new file mode 100644
index 00000000..b161a72f
--- /dev/null
+++ b/results/classifier/gemma3:27b/syscall/1728116
@@ -0,0 +1,50 @@
+
+
+
+Empty /proc/self/auxv (linux-user)
+
+The userspace Linux API virtualization used to fake access to /proc/self/auxv, to provide meaningful data for the guest process.
+
+For newer qemu versions, this fails: The openat() is intercepted, but there's no content: /proc/self/auxv has length zero (i.e. reading from it returns 0 bytes).
+
+Good:
+
+$ x86_64-linux-user/qemu-x86_64 /usr/bin/cat /proc/self/auxv | wc -c
+256 /proc/self/auxv
+
+Bad:
+
+$ x86_64-linux-user/qemu-x86_64 /usr/bin/cat /proc/self/auxv | wc -c
+0 /proc/self/auxv
+
+This worked in 2.7.1, and fails in 2.10.1.
+
+This causes e.g. any procps-ng-based tool to segfault while reading from /proc/self/auxv in an endless loop (probably worth another bug report...)
+
+Doing a "git bisect" shows that this commit: https://github.com/qemu/qemu/commit/7c4ee5bcc introduced the problem.
+
+It might be a simple logic (subtraction in the wrong direction?) or sign-ness error: Adding some logging (to v2.10.1)
+
+diff --git a/linux-user/syscall.c b/linux-user/syscall.c
+index 9b6364a..49285f9 100644
+--- a/linux-user/syscall.c
++++ b/linux-user/syscall.c
+@@ -7469,6 +7469,9 @@ static int open_self_auxv(void *cpu_env, int fd)
+     abi_ulong len = ts->info->auxv_len;
+     char *ptr;
+ 
++    gemu_log(TARGET_ABI_FMT_lu"\n", len);
++    gemu_log(TARGET_ABI_FMT_ld"\n", len);
++
+     /*
+      * Auxiliary vector is stored in target process stack.
+      * read in whole auxv vector and copy it to file
+
+shows this output:
+
+$  x86_64-linux-user/qemu-x86_64 /usr/bin/cat /proc/self/auxv | wc -c
+18446744073709551264
+-352
+0
+
+And 352 could be the expected length.
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